Hiruzen deserves to be the best Hokage. Introducing new and innovative policies is great, but it takes even more work and better leadership to implement them properly. Hiruzen did just that; he maintained an almost perfect balance b/w Tobirama's policies and Hashirama's ideals. The only bad part about Hiruzen's tenure was that he didn't do anything to correct Tobirama's mistake, and he let Danzo, the second coming of Tobirama, wield too much power.