Pein wants to see how everyone ranks in Akatsuki so he decides to hold a free for all battle. (This is Akatsuki as it was after Orochimaru left and before Tobi arrived).
Who do you think ranks at the top and who do you think ranks at the bottom and can you provide a reason for each?
For me it's got to be.
1) Pein. Simple, he has the rinnegan and he almost single handedly destroyed Konoha.
2) Itachi. For me this is also pretty simple. Kisame admitted Itachi was stronger than him and he easily defeated Deidara in their first encounter. He also beat Orochimaru with ease.
3) Sasori. There's a big debate here on whether Sasori or Kakazu should take 3rd place. For me, given his vast number of techniques and near immortality Sasori takes this one.
4) Kakazu. It's pretty close between Sasori and Kakazu, very close could be tied for 3 tbh. He has a vast range of elemental attacks but he has only 5 hearts which could be a weakness given Sasori has hundreds of puppets into which he could transfer.
5) Kisame. He has a massive chakra reserve and is pretty powerful having been able to take out the previous owner of Samehada. Samehada also gives him a big advantage allowing him to fuse with it and steal the chakra off his opponents.
6) Deidara. Often underestimated given his loss to Sasuke but has still shown himself to be a powerful ninja by beating Gaara. He has some deadly techniques but as far as skills in taijutsu and genjutsu he's pretty average.
7) Konan. She can fly and is quite versatile but she was beaten fairly easily by Jiraya.
8) Hidan. Hasn't shown himself to have great skills in particular field but his immortality gives him an edge over most opponents. Once he gets a drop of blood it's pretty much over but he'd be unlikely to scratch any of the above members without them chopping his head off first.
9) Zetsu. He's not very powerful and is used mostly as a scout.
Please try not to make this a flame war. It's fine to disagree with someone without the need to start insulting them.