I mainly play nice, for different reasons:
Fallout 3: I do things like wreak a bad guy's main base, abolish slavery, and give the Enclave a bad day, kill the Andale cannibals. mainly to spite the horrid nightmarish wasteland life where most people live in fear, and to carry the nice satisfaction that I'm making the Wasteland safer. though some rare times I take certain evil options as well, like killing Moriarty or Sister (guys who people get mad at you for killing regardless of if their jerks or not), or stealing crud from people when they aren't looking (which is actually pretty easy),
Shadow the Hedgehog: Black Doom was the main reason I started out going all the way good, 'cause I enjoy the idea of giving a middle figure to mystery men who think they can tell people what to do without good cause.
Mass Effect: eh.... I personally get the feeeling that with some Renegade options, that I'm not truly succeeding in anything, maybe I carry a genuine Paragon perspective on matters.
Infamous: okay, I don't have that game yet, but I got to play a small bit of it, and when taking the good options, I really felt I was being a superhero, and I'm a sucker for superheroes.