If given the specific option, "do this and be good or do this and be bad" I usually choose bad. Mainly because there are more games that force you to be good than there are that force you to be bad. I love having the option there and like to take advantage of it.
However, if I like the characters such as if I can choose to kill the main character's friend and be evil I won't. I'm a big fan of characters and can get very attached to them so if I have to kill someone I like off I'd rather not.
In sandbox games, though, I do whatever feels the most entertaining. Whether that be stealing cars in GTA or sliding on bodies in Prototype I do whatever I feel like. Of course though, those games don't really have a hero as the main character. So I guess I prefer to be bad!
