I'd be a vampire. And I'm talking, like, a Christopher Moore,
Bloodsucking Fiends type vampire. I'd be able to walk straight up walls, see auras around living things, turn into mist, I'd be practically indestructible and have superhuman strength and reflexes, the whole deal. And, of course, I would gain strength by sucking blood!
The two downsides: 1) I wouldn't be able to do stuff during the day (meh), and 2) there would constantly be a bunch of angry villagers after me trying to kill me. But I think the pros would outweigh the cons.
HOORAY, VAMPIRES!