The bigger person will always throw the harder punch unless they have a jacked up stance. Who was more effective with their power was no doubt tyson. He had better speed and technique. You have to be either really strong or really skilled to make it as an undersized heavy and tyson was both. Could a prime tyson beat Vitali in an equally impressive fashion? The size advantage would be insane and i'm not sure. He'd atleast give him a run for his money.

All-time most impressive puncher has to be marciano. Throwing out all the boxing stuff (highest ko ratio all-time, only heavyweight champ to retire undefeated, horrible at best boxing technique), look at the stats of his punches. When measured, there was as much energy (energy= force force= massXacceleration) behind his punch as an armor piercing bullet meaning if bullets were made at the size of his fist, he could put as much force behind them as a gun built to shot those bullets. That's enough of a force to send a 1,000 pound weight 1 foot into the air.

When a former sparring partner of both marciano and louis was interviewed he said louis hurts you with very brutal combos but marciano does the same if not more damage with one punch.