What level of power are we talking about here? Because if we're talking any superpower I'd take the ability to reshape reality as I see fit, thus encompassing every single possible superpower.
In terms of more conventional superpowers, though, it's a toss-up between teleportation and the ability to stop/manipulate the flow of time. The latter, used properly, is easily the most powerful whereas the former is probably the most useful.
it would have to be an all power psychic with telekinesis, mind control, the ability to move objects with thought and all that so if you did have a really cool power i could control you to do what ever i wanted and if someone tried to fightback cover myself in titanium metal so it would be really ******* hard to hit me lol
you people are noobs, it is all about having Dr.Manhattan's ( Watchmen) powers. He doesn't have a kryptonite , metaphorically speaking, and can't be destroyed.