What always interested me about Zoro kills Kaido, is that Luffy doesn't really kill characters, when I could see Zoro decapitating someone.
So, at first, before I got into the whole Moria/Zombie Kaido/Blackbeard Pluton thing, I thought Luffy would beat Kaido, someone other shit would happen like the Marines (with Vegapunk lol) invading, and then Kaido would get back up a few hours later to continue the fight, at which point Zoro surpasses his limits and decapitates the dragon.
Would have put Kaido on his own tier of antagonists (lost to Luffy, but got back up a few hours later to come back), and not take away from Luffy's victory.