Depends what youre best at
Spam= ohnoki, guy, kimmimaru, tobirama (cant think of the others right now
Combos= young and old kiba,young neji, young rock lee, all naruto's and all sasukes, (except SM and Taka IMO), asuma, minato
If you rely on awakenings then: Danzo, young rock lee, guy, minato, A, and other flicker characters are great, rock lee gets his super early, and danzo is almost OP in it... Pain's almighty push is super fast and does crazy damage, also if you play online or with your friends i would avoid awakenings such as susanoo, hachibi, or any of the giant transformations... For some reason dashing breaks the big guys combo every time, then you cant sub out of the combo, also spamming distance jutsu's destroys big characters