Re: Brains over Brawn. The truly strong, Minato and Hiruzen!
Kages Intelligence (catergorized)
Hashirama - Leadership Qualities, knowledge of power balances and other villages
Tobirama - Politics, development of the village (Academy, ANBU, Police Force, Chunin Exams).
Hiruzen - Bookworm. Knows all Konoha Jutsu. Probably studied most of the Konoha scrolls (look for Blaze Release's thread)
Minato - Quick thinking, strategic planning, great future insight.
Tsunade - Created the medical ninja system.
I highly doubt that the position of Hokage would be given to ninja who don't have a fairly high degree of intellect. Even if all we've seen from Hashi and Tobirama are large scale jutsu we can assume that these guys are probably pretty smart and not just all muscle.
Also, all four Hokage have come up with revolutionary jutsu. Hashi had his necklace, Tobirama had Edo Tensei, Sarutobi took basic Konoha techniques and made them even more advanced (Shuriken Kage Bunshin), Minato had FTG and Rasengan, and Tsunade has Byakogou. To create justu such as these is a testament to their intelligence and skill. I think it's unfair to label the Senju as guys who simply 'Get the job done'.