Hashirama was the one who founded the village in the first place, he even had to kill his best friend in order to protect his village. The only downfall of Hashirama would be his ideals in seeing that the village would make clans disappear. Tobirama was the one who really help shape the village, but he unwittingly caused so much tension between the uchiha's and the rest of the village. Hiruzen allowed Danzo's devices which completely messed up the village. Minato died way too shortly after becoming Hokage.
So my answer is Hashirama. But Naruto potentially will be the best one. Which is what the story is leading to.
gotta say tobirama. Built the village what it is and gave it its infrastructure. Created the government, anbu, academy, and the konoha police so i say him.
Lots of crap happened during Hiruzen's reign, but his was the longest, and he maintained Konoha's position as the strongest hidden village, and led the village during two world wars.