Akatsuki, Pain is extremely hard to kill, predicts the future by 5 seconds, and with one shot killed and leveled a village, not a small one either, and you have to kill all 7 forms, he alone could take on most of Organisation XIII, even though I like KH, and if you're not counting those who died or MIA to have the full Akatsuki, Hidan is immortal... Quite obvious advantages.