Maybe my first serious post, don't judge me.
I like Luffy vs Kaido because it brings the Manga to its roots, when
One Piece didn't take itself too seriously. I always
disliked Dressrosa because of Doflamingo.
This type of panel did nothing for me. I remember back in the day everybody was wetting their panties in forums about how badass and dark Doflamingo is but to me it was just edgy and cringe.
Oh, I'm about to disagree fundamentally here. First of all, One Piece has never been
too serious. Not today, not yesterday, not since chapter one, not ever. Even in an arc as serious and grounded as Dressrosa, there were still plenty of gags and ridiculous moments. Just look at Bartolomeo peeing in the coliseum.
Doflamingo isn't just built up to be a "badass cool," because reasons. Thematically, he is Luffy's ultimate enemy. Doflamingo's motif is manipulation. Manipulation and control of others. Luffy is supposed to represent freedom and liberation. So thematically, they are mortal enemies.
What made me fall in love with Luffy's character were arcs like Arabasta, Skypiea and Arlong Park, where Oda cleverly built up the villains through the eyes of their victims, so they always seemed terrifying to us, but then radically changed the tone when Luffy met them face to face.
Take Arlong, he comes from the superior race originating from the Grand Line. At first, the Mugiwaras are dicking around in Kokoyashi without a worry. Oda hypes up Arlong up in our imaginations by showing his underlings sinking Marine ships effortlessly, by showing Arlong terrorizing Usopp and lifting houses (it's more terrifying if it's Usopp), we hear about how Fishmen are 10 times stronger than humans, Arlong's shark teeth etc.
Then as the arc developped it starts becoming personal. Arlong's invincibility aura grows more in Nami's flashback, but so does his ruthlessness as he murders Bellemere and enslaves the entire village.
Through this build-up we take this villain super seriously, we fear for Luffy. And this is why I think One Piece managed to conquer the hearts of children, teenagers and adults all over the world; After so many chapters of people jobbing to Arlong, being terrified of Arlong, etc., Luffy finally meets Arlong face to face and he doesn't care.
He isn't scared, he doesn't respect him, he goofs around and mocks him. Arlong is just some dude to him. Oda builds all this illusion of the invincible foe through the perspective of powerless people, but when Luffy gets there, this illusion is shattered.
Luffy isn't scared and doesn't respect the majority of deplorable opponents he faces. He can be carefree, goofy, and downright clueless to their deceptive schemes, yet he also takes the threats these opponents make to his friends, his morality, his idea of freedom, very, very seriously. There has always been a balance. Luffy became deathly serious with Arlong, too, when Arlong suggested Nami was just a means-to-an-end tool.
He punches Charlos, the weakest guy physically, but the strongest from a political and influence perspective, for the same kind of reason. Because he humiliated a friend.
Luffy's character was too fucking cool. No matter how serious the situation was, he would make us laugh and never changed his relaxed/carefree attitude. Enel, the omnipotent God who was one-shotting everybody in Skypiea, looked silly trying to stab Luffy's Gomu Gomu no Baka.
tl;dr: One Piece is different from edgelord shit like Bleach (if you are a Bleach fan put your money where your mouth is and drink Bleach please) because it doesn't take itself too seriously. Oda manipulates the readers into hyping up the antagonist in their imaginations, only to have Luffy reminds us that they're just human.
The thing that is cool about Luffy's character, or at least has always been to me, is that he can
read the room. He's always known the things that are
worth taking seriously. Through Luffy we see what is valuable and what is not. Things like greediness, ego, so-called "genius," exploitation, power, etc. mean nothing to him. But the lives of others, the dignity of friends and family, the value of happiness and life, exploration and adventure, those are things he has historically taken
INCREDIBLY seriously throughout One Piece.
So, the fact that Luffy takes someone like Doflamingo who threatens his beliefs completely seriously, to the point where he screams "You're suffocating me!", is not only not edgy, it also makes 100% thematic sense and is in fact REQUIRED. Luffy's love of freedom actually necessitates that he hate the things which not only oppose freedom, but attempt to end it.
Pre time skip and for much of Post time skip, Oda isn't manipulating anything. He's flat out telling you through Luffy what matters. What are praiseworthy ideals and what are not.
My problem with what is happening in Luffy vs. Kaido is that Luffy seems to be bucking all of that for the most part, only to instead have a good time with Kaido now that he has awakened the Nika fruit. Luffy's not really reading the room at all, (except for the one comment he made when he returned to base about Pedro, Momo, Kin, etc.). In fact, in the Nika form, he's actively making things sillier, though things are clearly dire. In Gear 5, he's almost like a caricature of himself, instead of actually himself. And even Kaido is acting strangely. I don't like it too much, personally. It could be going somewhere, but I feel that Oda has become a little too self-aware for his own good in his writing recently.