I would be a timemaster; complete control of time. Stop it, speed it up, slow it down, go forwards and backwards in it. It would be awesome.
I would never have to worry about oversleeping, I would always have enough time to finish my work. Sure I would seem to age faster, but I would always have the time to do the things I want to do.
Knowledge would be the coolest power to me: I wish I could know everything about evrything. That would be totally awesome. There are so many times I think, "look at that idiot struggling with that computer, he should be more edjucated on them." and then I hop in the car and I have no idea what its made of, why its made of that etc. As an added bonus to this power I wish I could make anything I wanted. anything at all.