They have 2 different types of power. Ali's best punch besides his jab was a sneaky, lightning fast straight right, a pop shot type of right like Bhops and Floyd use. Holyfield isn't known for his power as much as his skills neither, but when going toe to toe he could muster up some serious power and is a great example of a smaller fighter using leverage against a bigger heavier man. I noticed this in the Tyson fights and the time he dropped Bowe and a prime Bowe at his best. Holy is the stronger puncher, but I wouldn't say more effective.
Something I am not sure if anyone has mentioned that the heavyweights generally fought with the smaller ounce gloves through the 70s. Both guys hit plenty hard, I would classify Ali as more of a ripping puncher and Holyfield as more of a traditional puncher. Jab=even straight right=Ali left hook=Holyfield I think it is fairly even.
how in god's name could you ever say Holyfield had a jab as good as Ali's, who had maybe the best jab boxing ever saw? And all these people saying Foreman just fell down all by himself, he did not. Ali didn't lose a round in that fight, contrary to popular boxing opinion, and he was blasting away on Foremen the entire fight. Foreman didn't waste all his shots either, again contrary to boxing mythology. He was landing heavy, solid shots to Ali's body all night long and got in some good head shots too. Ali just took them and fired right back. Foreman didn't just fall down. Ali blasted him out of there with an accumulation of punches and a hellacious right hand at the end of the fight that George couldn't take.
Ali could be heavy handed at times and drop down some nice punches. Holyfield was the more explosive puncher. In a lb4lb sense, though, it's Holyfield. From the time Holyfield started on the national scene at the Olympics, until, say, the first Bowe fight, Holyfield stopped just everybody he faced. After that, he was old and almost all he had left was an explosive punch (see the right hand shot in the Botha fight when Holyfield was 104 yrs old). That's what kept him going.
Both not very hard punchers on a raw power scale. I'd give the edge to Holyfield since he punched the more viscous combinations that through accumulation left the more devastating effect.
Ali was better at delivering his power, Holyfield is the slightly harder puncher. Holyfield had more physical strength behind his shots, but Ali threw sharper, more accurate punches that you couldn't see at his best.