Really interesting thread!
Hashirama - Couldn't bring himself to kill Madara, lacked backbone and couldn't impose his decisions, which would probably have made the Narutoverse a better place. He really seems to lack common sense. The only redeeming thing he has would be his strength and his good nature, which united Konoha. Other than that, he's quite frankly a terrible leader.
Tobirama - Though he did make the situation worse, he was already in a tight spot. His prejudices toward the Uchiha Clan were all justified, though he contributed to aggravate the tensions. He invented Edo Tensei, and that's a terrible thing, but he also developed Space/Time jutsu, which is now proving to be really useful. In the end, he really cared for Konoha, and made much more rational choices than his brother. It's up to personal opinions for him, but in my book, he did what a leader has to do.
Hiruzen - He let the Uchiha Clan get massacred. He let Danzo run wild with his own armed branch and experiments. He let Orochimaru become a MASSIVE threat to the village. He didn't do jack sh*t to make sure Naruto wouldn't be ostracized by the village (don't feed me the "He didn't tell Naruto who is father was to keep him safe" BS. EVERYBODY knew Naruto was the Kyuubi's host, and thus he was already a target). And ALL his actions had horrible consequences. A horrible leader, really. If Tobirama made the situation worse, then Hiruzen nearly dug Konoha's grave.
Minato - He didn't do much. Fought Tobi and Kyuubi, fair enough. He seems kinda immature though, not sure he would have turned out to be such a great Hokage after all. But whatever, I can't judge, he only did good things. (Though you can sorta blame Rin's fate on him, but I won't do that). A good Hokage
Tsunade - Errrrr... First, she seems really weak compared to the others. She had one opportunity to shine during the Pain Arc. I have mixed feelings about it. Would it have been better to directly fight Pain to stop him from harming more people? Was trying to heal the whole village a good idea? In my book, it was an okay reaction, so I'll let it go. But she really screwed up during the war council, when she talked about how to deal with Naruto. Gaara, who's 30 years younger than her, had a better understanding of how to deal with the situation... She was useful against Madara though. Mixed to negative feelings about her.
So I'd say it's between Hashirama and Hiruzen. I'll vote when I'm sure.