Hiruzen. He was so brainwashed by the elders and Danzo that so many horrible things happened in his reign as Hokage.
Let's start off with Danzo and Orochimaru. These two are obviously hiding something/dubious.. yet Hiruzen shrugged it off. He was supposed to be so smart, so intuitive like a lot of the Kage in general have been, but he still couldn't see through a fraction of what Danzo and Orochimaru were doing. Either that, or didn't think things would get out of hand. Which is a dumb move.
Not only this, but it appears that out of any other Hokage.. his reign brought the most conflict, isolation, and even war.
Then of course we get to the treatment of Naruto. Which I'm sure was thanks to the elder's input at the time. The way he was treated was horrid. He was just a child who didn't even know about the Kyuubi until he was 12. Totally unaware that he could lose himself at any point to this thing, not only that, but totally unaware as to why he got so much hate. There was no reason to segregate him like that. I know it's mostly for plot, but come on! That's horrible!
And finally we have the Uchiha. Even Tobirama probably wouldn't have gone that far. Plenty of Uchiha for decades had served the Leaf without question. It was only until they were shoved nearly outside the village and given a position that would get them hated/sideline them from real missions that they started to question what was going on and feel betrayed. Instead of hearing them out and fixing the issue, Hiruzen listened to Danzo and the elders that said "nah you know what? let's just get rid of them and not bother". Really? One of the most powerful/THE most powerful clan in the whole village, possibly the world with how they're set up (ok that's arguable).. A clan so powerful that has lent it's men, women, and children to fight for the village for decades and given you the upper hand numerous times in war/missions.. is just going to be tossed into a mass grave? Horrible.
So. Brainwashed. A lot of hate brewing from other villages, lands, and even his own people. Wars/attacks on numerous occasion. S-Ranked criminals allowed to walk around freely. Condoned abuse of a previous Hokage's son. Massacre/genocide of a prominent/crucial clan in the village. Yeah. He's the worst Hokage and I honestly don't see any accomplishments other than hindering Orochimaru for a few years after their fight.
Minato wasn't around enough and paid the ultimate price to keep his people safe and trying his best to allow Naruto the chance to live as a powerful shinobi some day. Which he did. If anything Minato accomplished the most in his short term as Hokage and father.
Tsunade did what she had to do. She started opening the village up a bit more and started the path that would eventually lead to where the world is now in Boruto. Not only that, but she wasn't swayed too easily and did things the way she though they should be done. A true leader. She stood up and fought for her people when she could, even playing a decent role in the 4th war before Naruto and Sasuke arrived full swing. Not the best Hokage ever, but she is one of the best.