Rinnegan. The perks of Kyubbi chakra are healing, super strength, and super speed, but you're still one person. If you were to use any of those powers in a non-peaceful way to further your progress, you'd become a target. It'd be cool not having to worry about freak accidents killing you & traveling fast but that's really the most you're getting out of it if you want to retain a peaceful life.
With Rinnegan, you can forcibly recruit protection, get people to empty their wallets, get people to hand you their guns, cast genjutsu onto interrogators that would otherwise suspect you, get others to do the dirty work for you, make a man think he's crazy, make everyone think that that same man is crazy and alienate him from everything but a cell, etc, etc, etc. The best part is that it requires no contact, so there's no fingerprints, no words, so there's no logs, and that it's so alien no one would seriously suspect you even if they did see the Rinnegan(which could be hidden by cosmetic contact lenses). On the peaceful side, having the ability to live for hundreds of years would be great.