In that case I’ll be voting Jinbe. He has the superior amps in Buso and Rage Boost.
Jinbe’s Buso gives a greater AP amp than Wano Zoro, who, with Buso was able to oneshot Killer who was comparable to his base, and his Buso gives him a similar Durability amp to Pre-Hao Coating Zoro, who could defend against an attack that would oneshot his base.
Jinbe’s Rage Boost boosts both his AP and Durability. Prior to being amped, he was getting cut and harmed by Who’s Who, but afterwards, Who’s Who’s fingers broke simply my attacking him. The AP boost is also significant because prior to the amp, Jinbe and Who’s Who were relative, but after, Jinbe was able to break his hands by grabbing them and then take him out with a single hit.
Even outside of his amps, Jinbe is still the most skilled fighter here (debatable between him and Harribel), and he has durability negation with each attack that can travel several tens of meters on air. Since Fishman Karate attacks are doubled under water, the range and strength of his Fishman Karate would be much higher than what I said above, as these all happened above water.
Jinbe has the heat resistance to resist Harribel’s boiling water, and he has good enough water Manipulation with Fishman Karate and Fishman Jiu-Jitsu to manipulate both Harribel and Kisame’s water-based attacks to use it against them.