Hashirama Senju. By far the most powerful Shinobi to have ever existed.
Holding the power to combat the combined forces of Madara Uchiha and the Kyuubi by himself (albeit until Mito appeared), there is no doubt that he was a man to be feared. Men and Bijuu alike feared his fabled Mokuton and ungodly chakra reserves.
And yet still, with all this power at his fingertips- with power no man has ever (and likely will ever) hold- his reputation was not insurmountable. For although Hashirama was a powerful warrior, he was no Shinobi. And despite all the power at his fingertips and his insanely magnetic charisma, Hashirama was by no means the greatest Kage.
No, that title fell onto his brother. Tobirama Senju was not the most powerful shinobi in history. And neither was he the most charismatic. Though he very much was the most feared and, ironically, admired. Quite a dichotomy no?
Though generally seen as stone cold, Tobirama was a kind-hearted man. He loved Konoha and all of her people. Though often clashing with the Uchiha clan, he did not despise them as many believe. No, to him they were just another clan that resided in the village. And Tobirama loved all residents of Konoha.
Despite his kind-heart, Tobirama was by no means weak-willed or gentle. He ruled over Konoha strictly and with a firm hand. Hashirama may have built Konoha, but Tobirama was the one who kept her strong throughout two World Wars, the reason that Konoha survived through these words wounded, but not defeated. The fear and admiration people held for Tobirama transferred over to Konoha herself. And for this reason, Tobirama Senju was the greatest Kage the Shinobi world had seen.
Hiruzen Sarutobi was a strange mixture of both his predecessors. He was peace-loving and incredibly powerful like Hashirama, and yet he was a once in a generation strategist and very quick to quash threats like Tobirama. He was genuinely a kind person, but he was not one anyone wished to cross.
When Tobirama sacrificed himself to save his students, Hiruzen was already a living legend by age of 19. The obvious choice for third Hokage, the future of Konoha was looking brighter than ever despite being entrenched in the middle of a second World War. Hiruzen would come to rule for a long long time. And he would become the most loved Kage in history.
To the Elemental Nations, Minato Namikaze was the epitome of Shinobi. The first person in history to have ever had a 'Flee on Sight' status. The first SS-ranked Shinobi to ever be recorded. No man- past or present- had ever inspired fear upon their enemies as he did. Not any of his predecessors, nor any of his fellow Kage ( or their predecessors). Not Madara Uchiha. Not Orochimaru. Hell, Iwa would have rather faced the Kyuubi twice over than even set eyes upon the Yellow Flash himself.
Minato Namikaze was a once in a millennium occurrence. He had power beyond most shinobi that existed. If he wished to change the environment around him, he could do so with nigh but a few hand seals and the whisper of a jutsu. If he wanted you dead, then you may as well just lie there and wait for shinigami to come claim your soul.
If he wished to cut you to pieces with his tanto, even the fabled samurai of the Land of Iron wouldn't dare stand in the way of his blade.
If he wished to alter reality, then with merely a few strokes of his brush reality would be clay for him to mold as he saw fit.
The man took the phrase 'Jack of All Trades and Master of One' to another level. There was no Shinobi art he was not superbly proficient in. From Genjutsu to Bukijutsu, Minato knew them all, and very well could contend with masters in their field.
Though despite this vast knowledge, he favored Taijutsu and his near inhuman understanding of Fuinjutsu to the point of near exclusivity. The man's feats were so insane, so far out of this world that they seemed like mere myths. People hear of his slaughtering of thousands of Iwa Shinobi in under 10 minutes and they marvel at it without even thinking that this single man has more kills under his belt than nearly half of the Shinobi in his village...combined.
People believe that his decimation of Iwas forces at the battle of Kannabi Bridge was the reason that Iwa entered peace negotiations but it wasn't the true reason. Iwa was still an incredibly powerful nation, it rivaled Konoha in strength. After the slaughter of over a third of their forces, they sent out their trump cards to defeat the monster that held the power to do such a thing.
Jinchuriki, commonly known to be army killers. Able to replicate the feat of the Yellow Flash, but not nearly as impressive as their power is borrowed. They sent out Han, Jinchuriki of the Gobi and Roshi, Jinchuriki of the Yonbi. Two legends in their own right. Combined they overtook the kill count of even Minato.
But when they were promptly returned to the Tsuchikage's office and dropped at his feet, only their demons keeping them alive, Oonoki had to admit defeat. What can your army do against a man who can soundly defeat two army killers himself and come out of it with no permanent damage?
When Hashirama died of old age, he was put on a pedestal above all others.
When Tobirama sacrificed himself, the world mourned the loss of one of the greatest minds to grace humankind.
When Hiruzen retired the first time, people rejoiced at the old man finally being able to rest.
When Minato Namikaze died taking down the Kyuubi, he was deified. For his defeat of the Kyuubi was what pushed people over the edge. No human alone could accomplish the feats he had. None could ever hope to.
Except Minato Namikaze knew there would be one more. Because not many knew, but Minato Namikaze was afflicted by a disorder only 1% of the world suffered. He was diagnosed with Muted Effect at a very early age. And while he learned to love the village, and he cared greatly for his students and Senseis, Minato Namikaze loved only two people in his life. And their names were Kushina Uzumaki and Naruto Uzumaki-Namikaze.
And while his emotions were very muted for everything else, for these two people, Minato Namikaze cared for more than anything else. And for these two people, Minato Namikaze gave his life.
And he wasn't worried about their safety after his passing. Because Kushina's reputation was very close to his own. She was an army killer, and the only one in Konoha with a kill count comparable to his own. Because for all the love and emotions and peace that Kushina exuded, when someone she cared about was threatened, she emulated every bit of the Kyuubi inside of her.
And finally because Minato knew that if there was one person that could surpass him, it would be his son. It would be Naruto.