I think for one punch, probably Ingo. I think when Ingo really was at his zenith the timing on his right hand gave him that extra “pop”. The connections that initially put Machen and Floyd over were so spectacular that they both appeared to crash land flat onto their backs so hard that they nearly went through the floorboards. It was if they had been dropped from a great height. But I never saw quite such power from Ingo again. He knocked guys out again after this but it wasn’t quite as stunning. The guy had heavy hands anyway but that extra special timing he had for a limited period allowed ingo to punch right through the target in a way he really had to be at his peak to produce it.
Both generally required lots of shots to finish off good opponents.Ingo hit Machen with everything bar the referee before he was stopped.Rocky maintained a steady, relentless bombardment until his man crumbled.