First thing I want to say is that the Hokage standard of Konoha fell kind of now. Shodai Hokage sealed all the Bijuu and delt them out like a crack dealer and duked it out with Madara and lived/won (Idk I mean Madara got a living clone of him so who really won right?) Tobirama...he just looked like a G and he made the shinobi organizational system that was the basis for everybody elses. Hiruzen, the Professor, we already seen him in action, Minato, again seen him deal with Madara (somewhat I mean he gave him a pretty bad injury on the arm and released his control on the Kyuubi) Now we got Tsunade and we haven't seen her beat any major ass in the series. She was able to heal people without being next to them and sheiled them from Pain's blast but compared to the other Kage she make Konoha look like a punk now.
On topic I think Tsunade is up to par with Raikage in strength (Physical not skill wise...but I think they like the same age or something), But I'd say that Gaara and Tsunade are the odd ones out of the other Kage. Raikage, Mizukage, and Tsuchikage in that order for me (Tsuchikage has more experience but his hip is gonna break at any moment I can feeling lol).
