I'm going to bet on Ryuma in extreme diff. I'm mainly basing this on his reputation and his exceptional mastery of armament haki.

Kaido. Even if Ryuma's armament is better, Kaido still has every form of advanced haki and has insane physical stats that bests most of the top tiers.

Kaido force is absurd compared to Ryuma,since he controls perfectly his fruit and has fully enhanced haki