Top ten in Part 1 obviously.
1.Hiruzen
2.Itachi
3.Jiraiya [Flame me for putting him after Itachi.]
4.Orochimaru
5.Gai
6.Kisame
7.Kakashi
8.Kimimaro
9.Tsunade
10.Naruto
Sasuke deserves no mention because he was weak in Part I. If Naruto would summoned Gamabunta during their last fight, Sasuke would have been crushed.
Kabuto also doesn't deserve a mention because he was weak in Part I. When Tsunade got over her fear of blood, he couldn't do anything to her.