I would think somebody like David Tua would be the hardest puncher... He is like 5'9 and 230 with so much power... I haven't seen as clean of knock outs as his against a Ruiz and Moorer. Also Foreman was very strong, but alot of times it took alot of punches from him to bring somebody down because he had no snap on his punches. Mike Tyson had snap on his punches, but with his wild swinging punches he didn't root his feet because he was just short he had a to leap at the guy which took alot off his power, or he would have the hardest punches ever. Earnie Shavers punched hard no doubt, but I don't think he hit harder than Tyson and Tua.