Everyone has thought about it. At least once or twice - what super power would you have if you could choose anything? Or perhaps, if just given the choice between flight or invisibility, which would you take? Only one choice, and you are the only one in the world to have that power.
With the price of gas today, who wouldn't chose flight? You could just zoom around whenever going somewhere, and as an added bonus, you could make a really good witch or wizard costume at Halloween.
Of course the invisible power would have its advantages, too - excellent for pranks and escaping a tight situation, but ultimately I don't think it would be a useful power for good, just a temptation of the opposite.
Shoplifting would become simple, and from that one could easily snowball into bad things. Anyway, one would have trouble being a super hero with either of those powers, if that was the only one they had. Unless you had super strength, or a super hero team to back you up, of course.
If I could choose any power, it would be a close decision between controlling time and controlling gravity. Time control would be both fun and useful, but the specific details would have to be worked out. If you went back in time a day, what would happen to the rest of the world - would they also go back? Could you meet your past self, or would there always be only one of you? It could get confusing if a new copy of you was made every time you time-traveled. After a while, there would be so many copies of you, you would definitely run out of clothes for all of your selves. And I suppose you could just stop time and steal some from the store, but hey, that's not proper conduct for someone posing as a super hero.
According to an online quiz, I would be Superman. I wouldn't want to be Superman though - actually I wouldn't want to be many of the super heroes - tragedy seems to be one of the prerequisites for gaining powers. Spiderman's uncle died, Superman's planet blew up, the X-men protect people who misunderstand them and countless other heroes have been exposed to toxic chemicals or radiation. I would imagine those must have been traumatic experiences.
I guess that's where their great sense of responsibility and virtue comes from. Even Aristotle supported super heroes (according to Wikipedia): "There are men so godlike, so exceptional, that they naturally, by right of their extraordinary gifts, transcend all moral judgment or constitutional control: There is no law which embraces men of that calibre: They themselves are law."
