Zoro created an entirely new sword style by combining a fully mastered Enma with Haoshoku: "En Ou Santoryuu".
"King of Hell: Three Sword Style".
It bears the name of Enma, but is written with the "King" from Haoshoku.
Oden's ultimate attack was Togen Totsuka. This is En Ou Santoryuu Zoro's ultimate attack:
It has the longest Haoshoku trail we've seen ever.
I place Yamato above because of the portrayal of Haoshoku coating, but King would definitely push her to her limits.
If there is anyone on Wano without Haoshoku coating that might beat Yamato it's King.