By their feats shown in the manga . No Edo Tensei included , this Akatsuki is all member in their prime (Prime Itachi , Prime Nagato , Prime Obito etc.)
Though I had some little doubts on who to put first but ...
1 - Nagato/Obito
2 - Obito/Nagato
3 - Kakuzu
4 - Itachi
5 - Kisame
6 - Sasori
7 - Deidara
8 - Hidan
9 - Konan
10 - Zetsu
Although you may disagree with 3rd place and 10th place , Kakuzu held his own against Hashirama and still got out alive from the fight . ABC logic is wrong but here I doubt that Itachi would be left alive from a Hashirama fight . Even so , Kakuzu has shown incerdibile feats in the manga . As for Zetsu I know that he has been relevant for past chapters and stabbing a Juubi jinchuuriki , but all he has for a power is being 'sneaky' . He still has a weak mokuton . u_u
Though I had some little doubts on who to put first but ...
1 - Nagato/Obito
2 - Obito/Nagato
3 - Kakuzu
4 - Itachi
5 - Kisame
6 - Sasori
7 - Deidara
8 - Hidan
9 - Konan
10 - Zetsu
Although you may disagree with 3rd place and 10th place , Kakuzu held his own against Hashirama and still got out alive from the fight . ABC logic is wrong but here I doubt that Itachi would be left alive from a Hashirama fight . Even so , Kakuzu has shown incerdibile feats in the manga . As for Zetsu I know that he has been relevant for past chapters and stabbing a Juubi jinchuuriki , but all he has for a power is being 'sneaky' . He still has a weak mokuton . u_u