Leadership ranking:
1. Tobirama (Properly establishing the village, organizing its laws basically he set up the settlement. Very strong leader by force of will not by empathy, an exemplar for a yin/yang view of Hokage) You could call him the founder of Konoha because while his brother and Madara shook hands you can bet your ass he was the guy organizing everything behind the scenes. That means he was a great administrator and diplomat managing to organize things between what had been disparate waring clans up till this point.
2. Hiruzen cannot be understated he is the longest reigning Hokage for a reason his leadership is likely second to none. However he waned greatly towards the end of his life. Strategic knowledge of waging war is also likely second to none amongst the Hokage. However he exemplars a "light" hokage not willing to dirty his hands unless there is no other choice.
3. Naruto (His ability to get people to empathize with him is second to none. That is a trait any real leader would give his right arm for, but not a leader by pure will, people WANT to follow him, they are not compelled) However strategically with regards to war I imagine he would leave the minutia to Shikamaru. Ergo his reduced standing in my view.
4. Minato (His attitude towards the village is similar to Naruto's, a Hokage very similar to Tobirama in nature not afraid to make the difficult decisions. I imagine he would have been a good middle ground between Naruto and Tobirama in style had he lived) Minato and Naruto are very close in my mind but because Minato died before his time his standing is reduced.
5. Hashirama (His charismatic quality is impressive but lacks a special something when compared to the likes of Naruto or Tobirama) But his short reign tells me he could not deal with the stresses of killing his friend and the position at the same time.
6. Tsunade in all honesty she was chosen for lack of a better candidate, her leadership abilities are pretty much fair but nothing special in my mind. She is a peerless support Ninja with great offense and defense abilities but a great ninja does not make a great Hokage.
7. Kakashi? I can't tell hes at the bottom for no other reason but because I can't judge from no information.