My sympathies lie with the well-developed bad guy. I don't find too many of those though; it's hard to break out of the "standard" bad guy trap, so all too often I run into bad guys who are psychotic or "evil" or sadistic or whatnot.
My favorite bad guy to write about is something of a masochist, who is on the bad side because it's a bit more "inclusive" than the scenario's good side--as far as shades of grey are concerned, at least--and also because the bad side is a lot more interesting. He finds the "good" versus "evil" situation rather amusing and especially enjoys playing the role of "bad guy." His major fault is a distorted sense of reality; he does bad guy things because it's expected of the role he's playing.
Actually, even I'm not entirely sure that he's not really a well-disguised good guy; the "good" side has some truly good individuals, but for the most part they are littered with rabid "good side" fanatics of the "anyone who's not on our side is an enemy" sort.
That particular thread is under heavy development at the moment though; I've barely gotten the characters and basic plot established, but I've got some good progress on them.
... overall though, I do end up developing more "good side" characters in my other threads, and masses of non-affiliated characters who are dedicated to a conflict that's completely different from "good" vs "evil." 3nodding