Zaraki Kenpachi - I have a bit of a lack of charisma in terms of...everything. ( a BIT! See that?!) The fighting prowess would be...well, it would be a nice break from reality.
Kanda Yuu - The ability to be an enormous douchebag, and still have it be considered socially acceptable by those around me.
Haruhi - The insanity. Really, have you witnessed anyone act in such a fashion, even remotely? Considering that I have a similar personality, though obviously to a lesser extent, I think it might be interesting to see what I might be like if my level of social-retardation were increased ten-fold...also, do you realize how much fun that child has?! It's just, Jesus...you'd never be bored.