I can't decide!!!!! I mean, assuming that b ninja you mean from Naruto. If no, then Keyblader! but if we are talkin' Naruto, can't decide.
Keyblader: giant sword that you can summon at any time, magic, Limits, Drive, overall coolness, possibilty of meeting Kairi.......and Sora and Riku, of course...
Ninja(Naruto-style!): metal headband, Sharingan, Shadow Clones, Fire Jutsu, Chidori, Lightning Blade, Rasengan, tons of other cool Jutsu, Demon Wind Shuriken.
But still, each has disadvantages. I can't pick right now. Maybe if I was forced into choosing onbe or dying, but not right now.