One of the extra complex forms a machine sprite can get is "any autosoft" but it doesn't say at what rank the soft is. How do I determine the rank?

Rank = Rating is the rule of thumb.

Yeah, that is my thought. It just gets crazy when their rating gets high.

i still wouldn't use a machine sprite as my first choice unless we're looking at a really high rating. for one thing, they can only have a handful of autosofts; you generally want at least 4, 5 if you're looking at more than one weapon on the drone (maneuver, clearsight, defense, and usually a weapon; for surveillance, you would probably replace with an EW autosoft, at a guess, but you might be able to get away with only 3 autosofts, or a rating 9 sprite)

so yeah, those high-rating sprites are good at some of the tasks they'll need to perform, but likely have holes in their skillset that a regular drone probably wouldn't. (provided you spend the cash for the regular drone to be effective).