This is a tough one. I want to say Duran but he is 67 years old and that could prove a factor if this goes long.
Broner don`t punch even nearly as hard as Hearns and Duran took Barkley and Hagler`s shots, they were great finishers at middle, how the hell is Broner going to punch harder than them?
sure he can, ab just doesnt like to let his hands go as much, but when he lets loose, he can beat anyone.
You think Broner could be the greatestr fighter of all time?! His chin isn`t strong enough to take Duran`s power and pressure, no way could he take the punishment Leonard took in Montreal.