You might be confusing people saying that he was the GREATEST light heavyweight puncher of all time with "hardest". I've never heard anyone refer to him as the hardest puncher in division history. His KOs were more often than not just a systematic breakdown of an opponent. Like Julio Cesar Chavez. One scribe likened Moore's subtle tricks when fighting to watching a mechanic working on an engine. A little tinkering here. A little tinkering there. Next thing you know the transmission falls out. :smoke
I'm not going to nominate Ezzard Charles as my pick as the best puncher ever, buthe deserves some mention. I wouldnt be surprised if he was able to KO anyone from 160-175, including Hagler, Monzon, Qawi, etc...
Shavers Foreman Liston Tyson Archie Moore It's debatable whether you rank Liston higher than Foreman or vice-versa, but Shavers I'd say is #1. Bob Fitzsimmons is definitely worthy of mentioning too.
Joe Louis was the best puncher of all time, but he probably wasn't the hardest puncher of his own era. Too many common opponents said that Max Baer and Curtis Shepard hit harder to dismiss them all. So I am going to be boring and go with Earnie Shavers.
On P4P basis Meza and Garza are both worth a mention, they some ridiculous combined record when they met. Khaosai Galaxy maybe? Finito Lopez is worth a mention as he was doing it at a weight where stoppages weren't common...
Julian Jackson MiD - Jimmy Wilde, Khaosai Galaxy, George Foreman, Earnie Shavers, Carlos Zarate, Tommy Hearns, Bob Fitszimmons, Bob Foster Maybe in that order as well