Tie between Muhammad Ali and Carlos Monzon for me. They were deadly accurate with their 1-2s at every angle or moving forwards or backwards.
Alexis Arguello Koysta Tzu Joe Louis Lennox Lewis Mikey Garcia is a current guy that doesn't waste very many punches.
Muhammad Ali ...it’s like whatever his brain told his hands to do ...they just did it ....he could have been a receiver in football
All of the answers thus far given are good ones.. But if I had to select just ONE I would choose Joe Louis.
By the numbers Floyd probably is the most accurate. But the thing is he usually only throws 1 punch at a time. And its a low degree of difficulty punch.
I wrote this about him in my article on the Cleveland Williams fight. "It was as if Ali's feet, hands and head all operated independently of each other. A sort of chimera of human movement, all his parts working towards different aims but with a sort of thoughtless, effortless coordination between them. Like 3 souls in the same body."