I'd like to be able to read peoples' minds, have the ability to make them be quiet when they're talking talking nonsense, and the ability to turn invincible.
An immortal necromancer with telekinetic abilities, a sword made from a soul so black it draws the light from a room and eminates darkness as if it WERE light, and a guitar that shatters the carcasses of angels when played. Oh, a trenchcoat and a Harley, too.
How about the ability to give a woman an orgasm just by touching her? It would come in handy, and I could have fun with it too. I could just walk the streets, tapping the shoulder of every woman I passed.
I'd want the ability to travel anywhere with my mind and like 'be there'. Like I could lie in bed but in my mind I could go over to one of my friends places and see what they do when they're by themselves. I reckon that'd be the ultimate power. Think of how much shit you could fuck up.