I think, honestly, most people would be a criminal, or some kind of antihero. Selfishness and desiring power is simply human nature. I'd love to have everyone under my command and being able to demand both respect and fear with a click of the fingers, maybe even partly as revenge for what society has done to me. But I wouldn't completely turn to the dark side, so I wouldn't kill people without batting an eyelid for my own gain, and I'd still occasionally try to improve other people's lives. When I got bored, I'd just fly into space and/or to other planets and check them out, but not destroy any.
As someone else said, I might just do a Dr. Manhattan.