Joe Walcott said that Marciano hit him harder with one punch then Louis hit him with 4. Good enough for me.
Archie Moore was probably a sharper puncher. He was also a slick counter-puncher--that's how he decked Rocky. But he wasn't a massive slugger. Rocky was the true banger between the two. But both men had their own techniques to knock you out.
Rocky. Moore had power and knew how to stop people (he does have the most knockouts on record) but most of the time he broke his opponent down using pressure, combinations, and accurate punching combined with good power. Rocky used pressure and sometimes combinations to break his opponent down as well but he had more one punch power than Moore. Moore was more accurate. Rocky hurt guys with punches that didn't even land clean sometimes... on top of the head, shoulders, arms, hips, etc. If he would have been more accurate he would have had more early KOs. I closer poll might be between Moore and Walcott.
Moore was a better puncher but Rocky hit harder. It's those sneaky shots that Moore mastered that also helped him stop opponents in his career. Marciano did hit very hard and I'm not sure if it's true but I've heard that his power equates to an armor piercing bullet, unreal.