Frazier was quicker, bigger and had slightly better range. Hard to say who had more power, I struggle to see Rocky knocking Ali down. Also hard to say who had the better chin, I struggle to see Rocky surviving two rounds with Foreman. But it's impossible to watch fights featuring them both at the highest level and reach any other conclusion than Frazier looked the more skilled HW. Whether those aesthetic skills would be enough for him to beat Rocky h2h is another question. I suspect so but Rocky proved many times to be superior to fighters with better perceived skills.
I'm biased towards the left hook but also rocky missed a lot more than smokin Joe. I'll give it frazier, I liked the way he rolled onto his philly hook