1. Kabuto (The only ninja I believe could possibly beat him is Tobi)
2. Tobi (Ghost mode is tough to beat)
3. Naruto (BM is insanely strong, the only reason Tobi is above him is ghost mode)
4. Madara (Rinnegan, not Edo)
5. Nagato (the paths are frighteningly powerful, tough to match up)
6. Hashirama (flexible)
7. Hiruzen (flexible)
8. Third Raikage (hardly seems possible to kill this guy)
9. Minato/Itachi (Minato's FTG is not overrated, it's a great weapon, and he uses it incredibly well)
10. Itachi/Minato (Itachi with his smarts and abilities and his Susano'o's weapons has a chance against everyone basically)
11. Kisame (That shark bullet is almost a one shot kill with the ONLY exception being Gai)
12. Bee (Perfect Jinchurriki makes him a tough guy to beat)
I included Kisame and Bee in 11 and 12 because I was not sure where to put either Hashirama or Hiruzen, since all we have to go on them is hype until we've seen them in their prime. Those two to me are flexible and could go anywhere, everyone else to me is in their proper position in my mind.