I'm posting in c/movies but including tv shows, anime, comics, manga, etc.
Personally I think the final war rig sequence in Mad Max: Fury Road is the most impressive live-action fight I've ever seen. The practical effects and choreographing are incredible and the fight keeps moving along by having the stakes raised and characters dying, it doesn't meander.
In animation it's harder to say. Attack on Titan had a lot of really well animated action (it used be so good, goddammit). The battle in Shiganshina in season 3 is the best, the narrative weight is so strong, the characters all have really good moments, the stakes are really high and the production is incredible, animation, soundtrack, sound design, voice acting etc.
Mob Psycho has the most consistently incredible animation of anything I've ever seen, I think the group fight against the teleporting psychic in season 2 is my personal favourite, even if it's not the flashiest, it's really well directed and just such a cool fight, even though it's not that long.
The ChainsawMan manga has a lot of good fights, the Falling Devil arc is like my favourite arc of anything ever, but that's mainly because of the characters. The art is stunning, Fujimoto at his absolute peak, but the action is pretty straightforward. I mainly love it because it's Asa at her best as a character, and Asa is my favourite character of anything ever.
Wow it was way easier for me to choose a live action sequence than animated. Honestly there's so much lazy action in superhero slop that Mad Max stands out so, so much.
There are definitely similarities, which makes sense since they are both essentially kings. But I would say the biggest difference is the presence or absence of something like chivalry here. I think in many ways Arthur and the knights run against the inherent contradictions of chivalry, while the wuxia heroes are typically not guided by that sort of code. They are just individuals who have cultivated the power to uphold or skip past the laws that would bind them, the opposite of the emperor whose power is the font from which law springs. The emperor sits at the top of a distinct hierarchy, which is fine for him since he's so enlightened and all, but when Nameless spares him and decides not to kill him, Nameless is proved to be his equal, which for an emperor cannot be allowed. It questions something that Arthurian legend does not imo, the very position of emperor and/or king.