A few cool things about Hancock..

Flying in bermuda..
The most important thing. I mean, flying is cool, but it won't be much fun if you have to do it in Superman/Spiderman tights or worse still, in the tin suite of Ironman. Hancock gets to fly in his bermuda, so it's cool at multiple levels.

No uniform..
Every kid (and many adults) hate uniforms. But Superheroes have to have one. Not so with Hancock, wear whatever you want, but get the job done (it's one of startup fundas too) (Plus it helps with self esteem. I mean, What self esteem would you be left with if you had to wear your undergarments on your pants, Superman estyle?)

No identity crisis..
Another widespread problem among Superheroes. They don't want to reveal who they are, so they (have to) go to great lengths to hide their identity. But everybody knows Hancock (he won't even wear a mask), so he can concentrate on kicking enemy butt.

No girlfriend..
Yes it's a boon. Almost all superhero gf get themselves in trouble and our SH has to 'make a choice'. No problems if you don't have a gf.

Flying in bermuda..
Err, I guess I already covered that :-p.