I think people are mixing up raw power with other factors such as speed, timing, snap, and accuracy/placement. In terms of raw power, Marciano has more power. He was knocking guys cold with 1 punch, even when he was losing. Marciano had mainly raw power and little snap, but that raw power would KO you with 1 punch. IMO there are 3 types of power.
1) Raw Power
The raw power that would knock you cold with 1 shot in a flash. Marciano, Shavers, and Cooney are good examples of this type of power.
2) Clubbing Power
Clubbing power is what Foreman had. A lot of power, and tremendous force, but most people would get up 3-4 times before just not getting up or the ref stopped it. These kind of guys, just like the raw power, rate very high on the PSI scales, just they have trouble keeping guys down.
3) Rounded Puncher
A rounded puncher is a guy who has a mix of things to get his KO's, but mainly TKO's. Tyson had this. A lot of snap and speed, which helps keep guys down, but neither of these are power. He had some raw power, but not enough to keep very many people down with 1 punch. He had great accuracy and timing too, which is another factor that will get his KO's/TKO's. You'll notice that with most of Tyson's KO's, the people were still conscious, just on queer street, big time. Like when Tyson fough Holmes, he knocked Holmes down 3 times in the 4th round, 2 completely legit, 1 with a little help from a push. Holmes was badly hurt for 2/3 of those, but the first one was the worst. Larry was really rocked by a great right that came over Larry's jab, he went in for a clinch, Tyson took a step back, and gave Larry a little push, and Larry went down, but was up at the count of 4. Then he was in survival mode, he lasted another 15 seconds, wham, went down again, mainly from being off balance, he was up at 3. Then Larry survived another minute until he was in the corner, through a right uppercut with bad intentions, but it got tangled in the ropes on its way there, Tyson landed 2 great right hooks in a row, some of the best he through, and Larry went down with 6 seconds left in the round. Cortez didn't even bother to count (him being him
) and stopped the fight. Tyson with 3 knockdowns, wasn't able to KO Larry, landing his best shots. Afterward, Larry said that Cooney and Shavers hit harder. Most guys say theve never been hit harder than Tyson, because they haven't fought anyone with massive raw power. Another example, Tyson's fight with Michael Spinks. Again, Tyson landed his best uppercut, possibly he ever threw, and it landed flush on Spinks's face, Spinks was down for the count, but he was only on queer street, not out cold.
Those were some of my points and opinions, I'll probably post more later.