I have a character concept in mind, something very "American Psycho:" a Street Samurai who screams or laughs like a lunatic while charging the bad-guys with a chainsaw (possibly another melee weapon, because iirc chainsaws don't get strength bonuses to damage.) The idea is to get NPCs to target me instead of the rest of my family. I'm leaning toward a MBW system for the twitchy-dodge-y-ness and IPs, and a high Reaction to avoid as much incoming damage as possible. I want to be armored, but don't want to be too bulky as that kind of kills the vibe of the character, although a WH:40k Space Marine-ish character would be pretty kick-ass, too. Perhaps further down the road...

So: what can I do to avoid as much damage as possible without toys like Combat Sense, relying instead entirely on 'ware, and what can I do mechanically to make sure NPCs focus on my character?

Move-by-Wire. Adds double to Reaction attribute and grants +Dodge skill (which is limited by 1/2 skill like the Adept ability and Reflex Recorder, be forewarned. Augmentation).
Platelet Factories (SR4A).
Trauma Damper (Augmentation).

You saw the chainsaw goodies I posted, right?

Oh yeah. That Chainsword especially works with the Space Marine motif.

What about getting them to target me over the mage or technomancer? I was thinking maybe Intimidate.

Or be big and screaming. That tends to work well.

Damage Resistance buffs, clearly. Platelets, lacing, heavier armor (perhaps eating an agility loss), and consider cyberlimbs, they add additional armor to your overall score.

..as melee weapon, what about Nodachi (Arsenal) (w/ Personalized grip, cost 100Y ) Reach 2, Damage (STR/2 + 4)P, AP -2,Avail 12R,Cost 2500Y..
(Troll/Orc) Street Samurai with high Str and Agi, Blades skill with swords specialization..it would be massacre...

Cyberlimbs also add to your condition monitor, dont they?

..yes, they do...
.. from Runner's Companion, there is quality Tough as Nails ( +1 Phys. Con track) (cost 10 bp)
.. if SURGE/metavariants are allowed..
Dermal Deposit- quality from Runner's Companion (cost 10 bp) (+1 B/I armor, that do NOT count when looking for armor penalties)

..always good idea to ask your GM for permission to use MBW as part of Cybersuite (to save money and essence)

Hmm... wonder if a mage could augment the tank's targeting appeal?

Spell:Geek the Mage Tank First!
Category: Illusion
(Realistic, MultiSense)
Type:M
Range: LOS(A)
Duration: S
DV:F (?) May need to tweak drain still
Spell Prerequisite: Must know the Foreboding Spell already
This modified version of the Foreboding spell makes the sense of dread it generates in the area to be channeled towards one target, referred to as the Tank, making said Tank seem much more dangerous than they may actually be, causing them to jump up to the top of anyone's targeting list.

Hostiles attacking the party will typically focus their attacks on the Tank first and must pass a Cha+Will (3) test each time they try to target anyone else or they continue to focus their attacks toward the Tank.
Note: This does not preclude someone from using AOE attacks, it just means they will be centered on the tank, so grenades and AOE spells can still potentially affect other players.
So don't stand too close, but then you shouldn't be clustered up anyway.
Those that do pass the test can attack other targets but still suffer a –1 dice pool modifier to all actions for each net hit scored by the caster, representing the distraction of trying to attack someone else while their natural inclination is to attack the Tank for as long as the spell is sustained.

Allies of the Tank do not need to pass the Cha+Will test to act, but still suffer a -1 dice pool modifier to all actions for every two (2) net hits scored by the caster due to the unnerving presence of the Tank while the spell is in sustained.
Sure he is on your side, but you are still keeping an eye on him out of the corner of your eye because he is just that scary.

Fixed that for you.

Nephritic screen or other toxin resist ware might be a good idea. If you take bullets too well, they'll find a plan B.

Away from my books right now, so I have a two-part question. Would you need to increase the maximum reaction by one or two to increase the augmented maximum? Does some combination of ware (other than MBW 3, which isn't exactly starting gear) give you enough augmented reaction for that to be worth it?

..Yes, you can do it by taking quality exceptional attribute, also Genetic optimization (from Augmentation) do it also. those two stack.
..Wired Reflexes + Reaction Enchanters stack ( more available and cheaper than MBW)

1) Going from 5(7) to 6(9) is a 2 point increase to the Augmented Max, but 6(9) to 7(10) is a one point, then 7(10) to 8(12) is another 2-point. It looks like going from Even to Odd is one, and Odd to Even is two.
2) MBW is starting gear. Restricted Gear + 85k.

4th Ed, at least.

??
going from 5(7),
adding exeptional attr. 6 ( 8 )
adding geneware 7 (9)..
natural max is 7, augmented max is 9.

raising Natural max Attr by 1, raises Augmented max. Attr by 1.. (not two)

lol, my daughter's gonna Inhabitate a fire spirit into a monofilament chainsaw so I can charge them with a flaming chainsaw...

No, Augmented Max is determined by the Natural Max x 1.5. SR4A, page 68, Attribute Ratings, second paragraph, third sentence. I'm pretty sure he said 4th Ed at some point, and I'm reasonably certain 5th Ed didn't change this.

Isn't this also the only time you round down as well? Augmented max for an attribute of 7 is 10, iirc, but isn't everything else rounded up in the game?

Pretty much I think.

In 5th Edition, Augmented Max is simply Current Stat +4. There is no multiplier in 5th Edition. So, in 5th Edition, the Character with a Natural 7 in a Stat has a Max of 11.

So a human is 1-6(+4)?

...

Yeah, good chance I'm just going to stick with 4th Ed.

Yep, 1-6 (+4)
Course, that means a Human has a Cap of 10 for all their stats now, instead of 9.

Yeah, but now I can't meet that Augmented Max with a score of 3. Well, I mean I can, but the Augmented Max is crappier. You know what I mean.

How are you going from 3 to 9 now? The only way I know is with cyberlimbs, but you should be able to still do that in 5th, right?

A Reaction 3 and MBW 3 give you a Reaction 9.
A 3 Reaction and Wired 3 + Reaction Enhancers 3 gives you a Reaction 9.

Oh okay, I was thinking strength, agility, and body and how they can only get +4 without getting into limbs, which I hate...

Or like, stats at 3 and a F6 spirit possessing, as distasteful as some find it. A couple other ways, but TJ hit the easiest.

..Muscle Toner R4 (bioware) (Agiliity) w/ restricted Gear
..Muscle Augmentation R4 (bioware) (Strenght) w/ restricted Gear
...for Body, Troll charc.

..using Karma Built (750 karma)

..just remember, only one Attribute can be maxed out in charc.creation..