Between the two most punches throwing fighters in the history I'd favor Pac mainly because he punches straighter and moves better than Pryor and thus I think he could land first. Pryor has the edge in power and perhaps combination punching but I believe Pac's advantages would be the deciding ones
I can't really decide but if i had to pick it's Manny. This is especially the case if it goes the distance. Pacquiao's balance isn't perfect but much superior to Pryor's. Manny can throw power shots from angles just as well as the Hawk, without leaving himself in position to suffer a knockdown from a counter with very little weight behind it. I see a minumum of two 10-8 rounds in Pacman's favor which would probably be the difference. Manny is one of the few fighters in history that can come close to Pryor in terms of stamina, power and the ability to throw power punches from a variety of positions. He's also a straighter puncher and a southpaw. I'll go with Pacquiao SD in a great one.