Or any other logias fighting.
Specially the ones who have fruit powers that are opposites.
Like Aokiji vs Ace.
Sure, at his current stage Ace would probably not even be able to do any significant harm on him, but with enough combat experience and a few years, he could take him on. Who'd win?
Also, the more perplexing one, Enel vs Kizaru.
Kizaru is made (presumably, but seems logical to assume that at this stage) out of light. And Enel is lightning. Both move at the speed of light, can explode shit and become light. So who'd win in a fight?