Liston 1 until exile. With the Williams fight being his absolute peak. Question is kinda ironic, but when was Holy's prime? It's very debatable. Either way, Ali was better than Holy and wins.
I think holy's being underrated here, I don't think It's comfortable for ali at all, tho he probably pulls it out over 12 or 15
My thinking is, Ali could hurt Holyfield. And if he manages to do so late in the fight, I most certainly can see him getting Holy outta there via ref stoppage.