Every Smash Bros game >>> any other fighting game, IMO.
As for other games, I actually really enjoyed Injustice: Gods Among Us, I thought that game was really solid
I've dabbled in some SF games, some MvC games, but they never held my interest any. I can't really say what the worst game is, though.
“Anna, my strong, terrifying Anna.” -Cas
"You lack the requisite spine and testicular fortitude to study under me" -Elodin