Zidane is one of my favorites, but "badass" usually doesn't come to mind when you think of him. FF6 has my favorite cast of characters but none of them can really be considered lead. Shadow is probably the most badass party member, but he definitely isn't lead. Butz barely had a personality to speak of. Vaan is.....Vaan. 'nuff said. I'd have to go with Squall or Cecil. Cloud just doesn't have enough personality.
EDIT: also, in the game's animation it does show cloud throwing sephiroth down the reactor, as opposed to his jumping down in the movie.
EDIT: also, in the game's animation it does show cloud throwing sephiroth down the reactor, as opposed to his jumping down in the movie.