One of the most common critiques I've seen towards Kakagai is that Kakashi doesn't care about Gai, or he only does so on a surface level (out of duty to a fellow shinobi of the village). However, we also know that Kakashi puts up multiple barriers between himself and other people to refrain from getting hurt the way Sakumo's, Obito's, and Rin's death hurt him, maintaining an aloof demeanor to detach himself from everything. However, there are multiple instances where Gai remains the few/ sole exception to these walls Kakashi puts up.
It is obvious that Kakashi's love language isn't physical touch or words of affirmation. It becomes clear later on that it is quality time - and who does Kakashi spend time with the most? Gai.
Even in his worst moments, Kakashi still tolerates and accepts Gai's challenges and presence in his life. Of course, on the one hand, we have Gai's restless pursuits, but this is Kakashi. He can easily shake off Gai and cut off contact with him if he truly wants to. But he doesn't. As a matter of fact, he doesn't only accept sparring challenges, but also the silly ones like Rock-Paper-Scissors that have nothing to do with furthering their skills as a shinobi.
They were even spending time together at a festival when Kurama attacked the village.
And later on, when Kakashi almost becomes Hokage and Gai proposes that they stop their challenges so that Kakashi can focus on his job, Kakashi is the one that opposes it.
Challenges aren't the only time they spend time together. It is shown that Kakashi and Gai deliberately spend time together as friends, and Gai trusts Kakashi enough to confide his doubts about his father's youth in him, and Kakashi trusts Gai enough to let his guards down and show his admiration.
In his retirement, when Kakashi can finally freely do whatever he whats, he chooses to spend time going on vacation with Gai and not anyone else. He could've gone by himself, but he chose to go with Gai and reminisce their past together.
He even pushes their futon together so that they can lie side by side (look at the way their blankets overlap).
So yes, Kakashi clearly does care about Gai more than he does for most people. He just shows it in a very roundabout way because, well, he's Hatake Kakashi.
This part is not canon to the manga. However, since it's the last moment where Madara summarises his action and what triggers him to start the Infinite Tsukuyomi. It's kind of a POV without being really one because there is no new informations to what he said. But usually we forgot this powerful monologue because...you know... the shadow guy in the back did what he did...😑... And we were so surprise by this plot twist that we totally forgot Madara's words.
"I just want to be the saviour that ends the long history of fighting amongst shinobi"
He embodied perfectly the anti-villain trope. Noble cause but horrific manners. And also it goes along with my headcanon here that Madara has always be groomed by his clan to think of himself as someone special chosen by the Divine. The God's complex is older that we thought. Madara reminds me a bit the Big Nurse in the movie Flew Over the Cuckoo's Nest, where she is convinced to act for the well-being of her patients while her acts are authoritarian and cruel. The only difference is that Madara is fully aware of his own acts of violence in order to reach is goal, in this "cursed world" as he said there is no other way, and it's also the only way he learned as a child soldier during the Warring state era.
Establishing Ninja village led to an increase in their military built-up which result in battles that turned into great wars...with countless lives lost. The battling of what became the first Great Ninja War, the second Ninja War, the third Ninja war... The fightings never stop. That's Hashirama's legacy to the Shinobi world.
His comprehension on the shinobi world leaves you torn. All is true, painfully true. Contrary to Hashirama, he lived long enough to witness with his own eyes (pun intended) every wars. There is nothing the main characters can possibly talk no jutsu with him because either they are too dumb (Naruto), or too indoctrinate in the Will of Fire to even consider other perspectives (Sakura, Kakashi). And generally way to young to have seen every conflicts he is talking about.
Sasuke's position at this very moment is the most interesting.
But Hashirama ultimately failed in reforming the Shinobi world
Notice as the camera pauses for a long time on Sasuke. It's only after a second rewatching that we realise at this moment Sasuke has reached the same conclusion than Great-Great-Great-Grandpa. He heard Itachi's version, Danzo's version, Hiruzen's version, Tobirama, Hashirama, and even Hagoromo himself... In comparaison Naruto has no idea of the big picture. On and on, Sasuke listened all of them and meditated their past decisions who led to the current situation. The Shinobi world needs a reform because Hashirama and his successors have failed somewhere, in their own admissions. And he, Sasuke, is driven to be an Hokage and makes a change he called revolution. He is young enough to not be totally disillusioned like his ancestor. And for once, Madara's old age is a problem. His accumulation of experiences and tragedies froze his thirst for life (Gai may call it The springtime of youth) to the point he rather forces everyone into a fake existence than let them live and progress on their own. He hate this reality and doesn't want anymore to let it grow. While Sasuke still wants to change this reality.
Is this your idea of a perfect world? You're just deceiving people.
It's so strange because finally Sasuke is acting like the main character should act. Being challenged not just physically but also intellectually by an opponent, and overtakes him. Because of his Rinnegan and his EMS he was the only one who protected team 7 under his Susanoo and potentially the only one who could have stop the effect of Infinite Tsukuyomi. He actually doesn't need Naruto. That's the reason later he said that he will kill him first, the 5 kages and then he will liberate people from the genjutsu. This character is so independent from the main story we could literally have his own sequel without mentioning team 7. Anyway back to the old lad...
People cannot show each other their true feeling
When I dissected Madara's mistakes, I've said before that one of his main goal was to find a way to reach people's heart but he gave up the idea very early in his life. He never found a way to fully trust others and no one in return ever trust him.
My opinions were pushed aside
I've always repeated again and again but we never had Madara's POV about what happened in Konoha when he was still part of it. What happened exactly with Iwa? Why did his own clan prefer to be close to the Senju (long time enemies) than trust their own leader? Why was Hashirama not able to listen to his friend's opinion ? Lots of people talk about him, but we never let him express himself. We speculate but in the end, his opinion is still a mystery.
Disclaimer: this is not to say that Gai is a perfect teacher, or that other Jonin-senseis didn't try their best. All I'm saying is that Gai is the most suited for this job and there couldn't have been another Jonin in the Naruto world that is more passionate about nurturing the next generation.
Gai genuinely cares about his students' dreams and aspirations and does everything in his power to help them achieve it.
Gai is the only sensei that asked his team what their dreams are. Even with dreams that are often deemed unrealistic like Lee's, Gai doesn't discourage it. He motivates Lee but at the same time acknowledges the difficulties that will come along with such a huge goal. Clearly, he's both realistic and ambitious, an anchor that grounds his students but doesn't hold them back from their true potential.
And when Tenten wants to discover different specialties, Gai encourages it all, even going out of his way to ask others to aid his student in her search.
When she's discouraged because things don't work out, he's there to offer words of strength and lets her know her efforts aren't futile.
Gai cares about his students' emotional well-being, not just physical health (even though it is true that he places emphasis on it)
In the Chuunin Exam arc, when Neji almost killed Hinata, Gai is among the Jonin that held him back, and it is clear that they've talked about the Hyuga family before. It's a sensitive topic that Neji doesn't tell just about anyone, so for him to open up to Gai about it means he trusts his sensei enough to be vulnerable.
As for Lee and Tenten, he's always their biggest support but it's evident throughout the series and the previous point so I won't elaborate further.
Gai cares about all of the kids, not just his students
This point really sets him apart from everyone else. Each of the sensei cares about their students deeply, but the affection Gai holds for other kids weighs heavily.
He's deeply concerned about Naruto's general well-being, wanting to help him and protect him.
In fact, he doesn't mind going against the village's rule if it means he can help the kids in some way.
And then there's him giving food to Choji, despite scolding him on the surface.
So, yeah, the man has his flaws, but you can't convince me that there's a better-suited shinobi to be a jonin-sensei <3