Welcome to Gaia! ::

1-Madara: Cause he's the leader

2a-Pein: Jiraiya's mentor/opponent for Naruto
2b-Itachi: opponent for Sasuke
2c-Orochimaru: if dying to Sasuke once wasn't enough he's obviously going to be back to challenge everyone again

3-Kisame: Cause he's been around as long as Itachi and hasn't gotten killed off yet

4-Deidara: He managed to not only beat Gaara, he beat Gaara on his home field where he had the advantage AND while Deidara forgot to pack all of his goodies. He also pulled off an amazing fight against Sasuke and went out in a fashion that was respectable for someone in Akatsuki.

5 or 6-Konan: Possibly fight Tsunade or Sakura or Karin..or something. More information is needed honestly.

5 or 6-Sasori: Might need to move up a spot to replace Konan depending. The fact that he only died because he CHOSE too says a lot about him I think, and was another death worthy of an Akatsuki.

7-Kazuku: He wasnt very well developed and was just there to provide a personality balance for Hidan, establish the First fought a lot of badass people and let Naruto show off his new Technique

8-Hidan: No development, was the perfect example of "your mouth making checks your [censored] can't cover", one trick pony that was basically used to as a motivation to make Shikamaru show off his end-all intelligence..and start him down a path to chain smoking.