There is so many te can choose from. But one of my preferiti would be regeneration. I could be an adrenaline junky and would not get hurt at all! W00t! :D
I would Amore to be able to fly, shoot laser eye beams, blow ice breath, but the one I would wan't most out of all these is to have super sonic scream!
I personally think it would be cool to be able to morph into any animal I wanted, o maybe to be able to turn things to stone like Medusa (minus the snake hair)