Does need to be hottest fire in the verse, just will be cool to see a decent power up and a little change after getting rid of raid suit.
Having hottest fire dont mean you have greatest attack power and you are stronger than X character.
Like we thought FS is a broken ability and Kaido didnt even use it until Luffy started going all out (G4 snakeman, adCoC, adCoA, FS, all combined).
King lost despite having insane durability, speed, and attack power.
Power scalers are always mad about something, I tend to enjoy both Zoro and Sanji, it does not really matter who is stronger if both get good fights and development.
I dont like swordmen in OP in general, but thats a different debate, when I say that I am thinking of specific mangas focused on sword battles (I think you will agree that flying slashes, CoA and CoC have over taken the pure swordmen fight style).
But according to OP standard swordman Zoro >>>> no doubt.