Marco and WB are better than King and Kaido character wise. Their duo and their individuality
Marco and WB are better characters, but Kaido and King are a better duo.
Marco was amongst Whitebeard's "sons".
Just his strongest son and hence essentially filling the role of RHM. There was no distinction otherwise, between Marco/Jozu/Vista.
Kaido/King was an actual duo, with King being his official RHM that Kaido chose, and Kaido's first crewmate. Beast pirates formed with Kaido and King, like how SHP formed with Luffy/Zoro and Roger Pirates formed with Roger/Rayleigh - with their
They both had flashbacks about each other when they were defeated.
As a duo, there is no better ones aside from Luffy/Zoro, Roger/Rayleigh and (future incoming) Shanks/Ben - all of whom happen to be the partner type RHM who have similar portrayal to their captain rather than outright inferior portrayal. Makes sense, since they are conquerors themselves.
RHM dynamics:
- Roger/Ray, WB/Oden, Shanks/Ben (?), Luffy/Zoro
- Kaido/King, Crocodile/Mr 1, Doflamingo/Vergo, Blackbeard/Shiryuu (?)
- Whitebeard/Marco, Big Mom/Katakuri
- Moria/Absalom, Buggy/Mohji
- Enel/Ohm
Meh, too much to pay attention to lol. Plus, was a casual reader pre rooftop