Okay, I will reference the databooks. Stat wise, the only kages with databook stats are Tsunade, Hiruzen and Gaara. 35,34, and 29. Now, Gaara is young so lets cut him out. The next databook will show gaara much stronger now than the last. Tsunade is in her prime at the time of the stats, Hiruzen was past his. THE ONLY MEMBERS WHO HAVE BEEN GIVEN RATINGS HIGHER THAN 34 ARE ITACHI AND SASORI. Now, the only member who has been given stats above a Hokage in their prime is Itachi, with a 35.5, Sasori has a 34.5. And we all know how weak we like to call Tsunade. Guess what. She is at least 2.5 points higher than all the Akatsuki except for Itachi.(Nagato and Tobi have no rating yet).
Deidara- 32
Hidan- 31.5
Kakuzu- 32.5
Kisame- 32.5
^^^^^^^^^^^NOT KAGE LEVEL. All of these characters were defeated by characters not Kage level. Sasori was as well.
I know these stats aren't completely accurate, but do you really think Kishi would give someone a rating higher than another character who he thinks is stronger?