for me

5. Spawl Sites - I like to take the encounters in the back and flush them out into full runs
4. Seattle - Great streettalk and run ideas.
3. Mecruial - Its pretty terrible but the ideas are fantastic, I've rewritten and ran this thing more times than I can count and my players never get tired of the rewritten versions.
2. Street Samurai Catalog - Nostalgia really, it was my introduction to RPGs and Shadowrun as something more than a board game.
1. Seattle 2072 - Great Update

London Source Book
Rigger Black Book
Field of Fire
SR4A
Street Grimoire

(in no particular order)

London Sourcebook - I like this book, particularily the lively shadowtalk and the mix of detail and interesting stuff. The most under used setting ever.
Seattle Sourcebook - my introduction to shadowrun, and the first location sourcebook I liked. (Germany SB, curl up and die)
Paranormal Animals of Europe - so many nice ideas here.
Fields of Fire - if only another book like this would be published.
Berlin (German only SR4 publication) - brings the old city books back. And sells. apparently.

Denver had to go for Berlin. Bye Denver.

No particular order, because they're all the best books ever.

1. SR4A
2. Shadowbeat
3. State of the Art 2063 / 64
4. Year of the Comet (Ooooo, I liked SURGE and Ghostwalker too!)
5. Bug City

Shadows of Europe
New Seattle - incredibly useful
SR4A (It's so pretty...)
Prime Runners - awesome art
Underworld SB - so many ideas

Target:Awakened Lands deserves honorable mention.

1.) Threats 2
2.) Threats 1
3.) System Failure
4.) Burning Bright (Novel)
5.) Corporate Security Handbook

SR4A
Universal Brotherhood
Shadowbeat
Fields of Fire
Seattle Sourcebook

Bye
Thanee

I haven't read nearly as many of these books as I'd like. Laying hands on them with a limited budget is a bitch. So a For-Now list:

Dragons of the Sixth World - makes out just how different each GD is
Corporate Download - lots of story ideas
System Failure - exciting story
Aztlan - nasty nasty secrets and lots of politics

I liked other books too, but these really stand out for me so far. But people, please, please, elaborate on why you like those books

Not in order:

Seattle Sourcebook (original) - Not just nostalgia, still the best version IMO.

SR4A - Good looking book and 4th ed is my favorite overall.

Harlequin (the first) - mostly nostalgia but boy did we have fun with these in the early 90's.

Feral Cities - I've gotten good use out of this one running one-shot missions to Lagos and Chicago.

DotA series - I'll likely get some flak for this but I've managed to take the core ideas and events from this flawed series and rearrange and mangle them into a form that has been very enjoyable for myself and my group. Hell, I even managed to get them to form a bond of camaraderie with Jane.

Surprised nobody's mentioned Man and Machine. That was one of my favorites for the Hatchetman fluff.

Tir Tairngire
Shadows of North America
Seattle 2072
Corporate Guide
SR4A

Oh, you want to know why? Should have asked then!

1. SR4A - Beautiful book, well laid out, exciting to show people, really great fiction and artwork. It's *the* book I take out to show people SR nowadays.
2. Shadowbeat - Lots of cultural stuff about the Sixth World. Gets a little too punk-y for me, but still, a good birds eye view of the world.
3. State of the Art 2063 / 64 - Specifically, the culture sections in the back. Everything from news stories to the Top Ten Most Wanted for each respective year, they give you little tidbits about gambling, the current sports season, what music to listen to, private author in-jokes - just one of the best written fluff books for a gaming system ever.
4. Year of the Comet (Ooooo, I liked SURGE and Ghostwalker too!) - Lots of plot stuff. Introduced Ghostwalker and changed up Denver. SURGE. Comet Fever. The Comet Race. Just a good, thick, plot book.
5. Bug City - You know that scene in 28 Days Later when the protagonist is running through a church, and someone's written, "The End Is Very Fucking Nigh!"? That's what Bug City feels like. Or combine, as they suggest, Aliens with Blackhawk Down. The fact that it's written entirely as a set of articles posted together on a web service literally held together by glue, paperclips, and hope. And the fact that when the outside world got a look at those documents? They were six months old. Not to mention one of the best intros ever written. Bug City is scary, and it's a challenge, but the theme is, we can survive.

1: Shadowbeat
2: Shadowbeat
3: Shadowbeat
4: Shadowbeat
5: Shadowbeat

(Ok, seriously now)

There are just too many books to come up with a listing offhand, so this may be (aside from the obvious top choice) biased towards books that have been released as PDFs that I can skim to review the contents of.

1: Shadowbeat. Far and away the top—it adds a huge amount of depth and richness to the world by making the flavourful background concrete. How do you play Combat Biking? Shadowbeat gives you not only the rules, positions, and layouts, but the history and the team names. What's the culture like? Four pages of trid listings, with ads ("Half man, half machine, all heart! His only mission…destroy Antarctica! RAMBO VI", "Need money fast? Lonestar can help! Lonestar will pay up to 1,000¥ for any information that leads to a criminal arrest! Just call LTG# 307 (71-NARC) 24 hours, 7 days a week"). If you need to damage a target, and you come up with the idea of "leak damaging information to the press", will anyone care? Those rules are in there, with modifiers based on who's involved and what kind of damaging information it is, as well as what kind of risks the reporter will be running. A contender with Horrors for Best RPG Book Ever (Horrors beats it in setting-building, it beats Horrors in world-building).

2: Seattle. Like Shadowbeat, but less so; on the other hand, superior in immediate practical usefulness.

3: NAGRL. Also like Shadowbeat, but less so. More or less a whole bunch of answers to "how does foo work in the Sixth World?" Bonus points for the full-page colour ads for some of the new gear. Are we seeing a pattern here? Really, the two pillars that make Shadowrun such a great system are its impossibility-avoiding base mechanics (variable TNs, exploding dice) and the way that it has a world, not just a setting. If you want to know the hot clubs, you don't need to ask your GM. If you want to know the prisons, you don't need to ask your GM. If you want to know what's on the Trid, you don't need to ask your GM. It's just such an incredibly freeing experience, being able to separate campaign-building from world-building.

4: Rigger 3 (Revised). Probably the most obviously flawed entry on my Top 5 (*cough cough*diesel engines*cough cough*), but this makes the Rigger a fundamental component of a team, on par with the mage or decker. Notable for being the only case I'm aware of of sane design/customization rules in Shadowrun (not entirely sane, mind you—the chassis modifier thing and the miserable statlines for certain chassis/powerplant combinations need fixing, for example (you can't build a non-awful T-bird)), as well as helping expand the scope of the damage system and a whole host of other little things.

5: Lone Star. A pretty important organization. What are they like? Now you know. What can help you get away with things? Well, I'll quote a short section: "Spent my payload from both launchers and blew the [Fuchi] rotorcraft to twisted, burning scrap metal. Then the drek hit the turbofan. Lone Star light panzer dead ahead. Saw everything. Pulling its missiles on-line. Mine were spent, and going at it with my front guns would've done as much damage as throwing gum wrappers. I slowed to a dead stop. The cops in the panzer asked us who the frag we were, and I started sweating lead. We had enough restricted weapons and cyberware on us for them to send us up for a long time. Lucky me, I remembered that Fuchi had just signed a contract with Knight Errant. So when the Star boys asked what we were doing, I told them the truth. I said we'd just finished one of the wettest runs I'd ever seen, we had candy from a top-level datasteal, and Fuchi would spit teeth for a good three months if we could just dump our data on the market. Then I slid my window down and held out a bundle of ten 500-nuyen credsticks. I dropped them on the blacktop and closed my window. After a long silence, the Star cops gave us a warning about breaking the speed limit and told us to beat it."

Edit: oh hell, I don't have room for the Denver Boxed Set

~J

In no particular order:

Threats 1
Berlin (german-only)
Seattle 2072
SR4A
Cyberpirates

In no particular order:

Bug City.
Year of the Comet.
Shadowbeat.
Sprawl Sites.
Awakenings

There are a lot of other books that could make my list as well. A handful of adventures (Mecurial, Dragonhunt, Bottled Demon, Missing Blood/UB, Paradise Lots), a lot of the core books (Magic in the Shadows, SR4A, SR2, FIelds of Fire, Rigger Black Book, STreet Samurai Catalogue, Shadowtech, Cybertechnology), and a lot of other sourcebooks (The SOTA's, Cyberpriates).

But the ones above have probably been either the most generally useful, informative, or were instrumental in shaping how I see and think about SHadowrun.

Probably says a lot about me.

And Apathy: I think you're thinking of Cybertechynology, that was the second edition book that had the story about Hatchetman going full Cyberzombie.

Bull

Man and Machine
Fields of Fire
Mr. Johnson's Big Black Book
Corporate Security Handbook
Neo-Anarchists Guide

Which one? There were two

~J

The long version:

1.) Threats 2 - I like conspiracies and supernatural menaces in my games. And Threats 1 & 2 are quintessentially that.
2.) Threats 1 - See No. 1.
3.) System Failure - The same as No. 1 and 2. Skyn... err... Deus is a bit boring in my opinion but Winternight is one of the greatest villain group I have seen in RPGs and it fits perfectly into the Shadowrun background as a amalgam of technological and magical threats.
4.) Burning Bright (Novel) - The most well-written Shadowrun Novel and Bug City is simply great.
5.) Corporate Security Handbook - A surprisingly profound supplemental to make "standard" runs challenging and genuine.

There were definitely some great write ups out there. Hatchetman, Renny, Franks Cyberzombie piece, Matador in Fields of Fire, and IIRC, the detective in Awakenings, death of Captain Chaos. Good stuff.

In no particular order

1. Dunklezahn's Will
2. Bug City
3. Man and Machine
4. SR4A
5. Seattle 2072

Honorable Mentions: Harely Quinn, Renraku Shutdown, Brainscan, and Super Tuesday

1. Shadowtech: Anyone who didn't list this book needs to turn in their fan card. FANTASTIC book that is in the all time top three of RPG tech sourcebooks period. Still well worth getting ahold of a copy.

2. Shadowbeat: Still my favorite genre sourcebook for a roleplaying game. The reporter/musician mechanics are a bit wonky but damn it if they were not totally flavorful wonky mechanics!

3. Tir Tairgnire: Sure a lot of the stuff still makes me grimace (and I'm a million times more laid back than when we did SONA) but it's an interesting setting if you do some selective editing Good god that cover art is HORRENDOUS though. Egads.

4. Burning Bright: Read this book. Seriously.

5. Street Samurai Handbook: I remember when I first got this book in my grubby little hands. Young firepower munchkins unite!

In no particular order

1.) Shadowtech
2.) Feilds of Fire
3.) SR4A
4.) Renraku: Shutdown
5.) Cybertechnology (The Hachetman story is still some of my favorite fiction)

Honorable mentions for Threats 1 and Eye Witness.

[sarcasm]I'm shocked.[/sarcasm]

Yeah, don't know what might have tipped you off...

<----

Actually I've always been partial to the biotech/medtech/cyberware books.

1- Cybertechnology- As mentioned, the Hatchetman fiction is awesome as hell.

2- SR2 Corebook- The first book I flipped through and read. My copy literally fell apart, but I kept a few select pages. It's what introduced me to Shadowrun.

3- Cannon Companion- Gun modification rules rule! Okay, mainly it was the illustrations, they were just awesome as hell. Still, I recall a pistol I made for a hyper paranoid character, loaded with all sorts of features so he was the only one who could fire it!

4- Harlequin's Back- Huge Astral Quest. Lots of fun for the magic's sake. I loved the tweaks and what not to the various realms. And yeah, the plot of an epic plot of slowing the "Enemy's" approach isn't that bad, if you don;'t mind that aspect of the old SR/ED mix and mingle.

5- Shadowrun Companion 3rd Ed.- Again, the fiction here is awesome. The write up for alternate compaign concepts (from street gang, to DocWagon, to Spec. Ops for various governments) is awesome.

And since Shadowtech can't be excluded lest one loses their fan card, it's sort of an unofficial six. Awesome. I so wanted to include that one in here as well.

Shoud it even be suggested to make a 5 least favorite SR books? Or are there enough threads about WAR! already?

SR4A - Great book for a great system, and top-notch presentation.

Sprawl Survival Guide - Always been near and dear to my heart. I felt like it really fleshed out parts of SR3 and made the world feel alive.

Augmentation - This is my favorite of all the core rulebooks for SR4. I loved the layout, the organization, and I even had a Biology professor who was impressed with some of the real life science integrated into it.

Runner Havens - Seattle, Hong Kong, Caracas... some of my favorite settings. Even though Seattle was a bit boilerplate, the Hong Kong write-up was nothing short of incredible.

Corporate Shadowfiles - True story: I have a friend who is a lawyer and took a class on corporations and corporate law in law school. He didn't buy the several hundred dollar textbook. Instead, all he used was Corporate Shadowfiles. He made a B+ in the class. If you want to know how the megacorps REALLY work in the world of Shadowrun, you should get a copy of this book.

In no particular ranking:

Shadowtech
Renraku Arcology: Shutdown
Bug City
Corporate Shadowfiles
Aztlan

Fields of Fire - Used it until it disintegrated. Always will be my favorite book.

Bug City - Creepy and awesome. The theme is similar to your standard zombie invasion scenario but so much more vile.

Lone Star - They'll always be my favorite.

Awakenings - Its for a personal reason. My copy got water damaged, I put it in the oven on very low heat to dry it out, then I turned off the oven and forgot about it. When the roomate preheated the oven to make a pizza, a horrid stench wafted out of it. We opened it up to find that my SR book had been burnt and browned and looked really freakin cool. Punch some holes and bind it with twine and suddenly its a brittle and smelly ancient tome.

SR4A - Rekindled my old love of the game. What a great book.

Tir Tairngire: Probably my all-time favorite fluff book, and inspiration for more of my characters than any other single product I can think of. I'm a shameless elf fan, I love the extra dose of fantasy the Tirs put into Shadowrun (to clash with the chrome), and as a long-time Earthdawn fan I like the old products with the crossover fun.

Man and Machine: I got ridiculous mileage out of this all through SR3, and learned it like the back of my hand.

Cannon Companion: Ditto. This and M&M were my "go to" books for some of the best Shadowrun I've ever played.

Lone Star: A close second to Tir Tairngire for fluff-love (with some crunch mixed in). Just a great sourcebook, that turned Lone Star from just "meh, the cops, or security guards, or something" into a very deep, real feeling, organization...that ran the gamut from Barney Fife dorks to real, real, scary motherfuckers.

SotA 2064: I dig adepts. I dig spy backgrounds. I dig cop backgrounds. It was hard for me not to like this one. If I could pluck out "Old World Magic" and replace it with "Soldiers of Fortune" (from SotA 2063), I'd have just about the perfect book. Not because Old World Magic was bad or anything, but because adding mercs to a book chock full of adepts, spies, and cops, would pretty much be something like a chargen Bible to me.

Honorable Mentions go to Elven Fire and Dragon Hunt for published adventures I love (with special kudos to Blackwing and the Ancients), and while I'm cherry-picking chapters I'd have to give major props to the sections of Shadowbeat that deal with sports. I'm a major Urban Brawl and Combat Biker fan, even if I never got any use out of the rest of that book.

The adventure Queen Euphoria was and still is my favourite adventure. Before the secret was out, before bugs where known about, there was fear in the eyes of unready runners.

It's really hard to choose. Since everyone is already posting two of my top 5, please assume that Shadowtech and Shadowbeat are on here, and I'll go with the next 5.

In no real order :

Fields of Fire : Full of great info and wonderful plot threads in the shadowtalk.

Neo-Anarchist's Guide To Real Life : Everything I ever wanted to know about the lifestyles of the chronically poor and shadowy. Really helped to get the little details right when I was running game.

Wolf and Raven : If only for Kid Stealth demonstrating just what it's like to be friends with someone riding the edge of cyberzomibe status, and getting to ride along on Valerie Valkyrie's reality filter. This book did a really good job of blending magic, matrix, and manpower.

Virtual Realities : Let's face it, I love the Matrix.

Sprawl Survival Guide

Shadowbeat - Everyone covered this. One of the single best "flavor" books you can get.
Shadowtech - Bio has been my personal fav since this book.
Fields of Fire - We really need a version of this made for 4A.
Cannon Companion - All around grade A bang bang.
Cybertechnology - Worth the entry just for the fluff.

Honorable mentions Street Samurai Catalog, the SOTAs, and Man & Machine.

Yea, I played lots of Sam's back in the day. Actually, I still do. But a lot of the books on my list are in there for the fluff. When you get a new book and you can't put it down because the fluff has pulled you in (rather then skimming, then flipping right to the crunch), the writers have done a great job.

Wow, my first double post glitch.

Some of my favorites are:

Universal Brotherhood - I love how it mixed an adventure with game information.
Bug City - No need to explain why, plenty of people have done this already.
Corporate Shadowfiles - I don't believe any of its successors ever included an introduction to how corporations work that was as good as this one. The one in Corp Guide doesn't come even close (and sounds like it was actually written by a corporate apologist).
Sprawl Sites - This one is just fun to read, and you can extract several mini-campaigns out of the "random encounter" lists if you run them in sequence. The actual locations detailed would need some updating for SR4, though.

There are lots of others, for lots of reasons, but these four are the ones who jumped to my mind.

Street Samurai Catalogue
Rigger Handbuch (german Rigger Black Book)
SR4A
Denver Box
Cyber Pirates

In no Order:

SR4A: for getting me back into one of my favorite Game Worlds after 3e left me behind.

Deutschland in den Schatten (Germany Sorcebook): For giving me the magnificent Sprawl of Groß-Frankfurt, and thus handing me the means of scaring my Players for a LONG time

Shadowtech: This book - together with Fields of Fire really brought the Shadowrunner subculture - and the world - to life for me.

Sprawl Sites: Another brilliant book for bringing the game to life for my group - especially as my german copy fell apart and I could use it as handouts...

Corporate Shadowfiles: I hope I got the right one, german title was Megakons. Helped make the world make a lot more sense

1 through 5 - WAR!

"Oh this is going to hurt."

Keep your trolling to the War Troll posts

Dragons of the 6th World
Dunkelzahns Secrets: Portfolio of a Dragon
And even though the way it was done was dumb, the way it was written System Failure was good enough.
Seattle 2072 because it's an update on the main playground, even though i don't like what happened to some of it.
And i am rather liking the Berlin Source Book.

Yes, i am a sucker for fluff . .

My favorites include:

"Sprawl Survival Guide" - a great book for fluff and introducing new people to what being a Shadowrunner is like.

"Runner Havens" - because Hong Kong is awesome, though I wish that Istanbul had been made the second expanded city instead of Seattle.

"SR2" - because it introduced me to SR. Well, that and a con game in the early 90s

In no particular order:

Corporate Security Handbook.

Corporate Shadowfile

Harlequin's back

Neo-Anarchist's Guide to Real Life

Cybertechnology (pretty close to Shadowtech)

...Shadowbeat.
...London Sourcebook.
...SOTA '64 (and agree with Critias, if the Merc stuff were included it would be the almost perfect supplement).
...Neo Anarchist's Guide to Real Life.
...Man and Machine.