GGG as he's more complete and more talented in general. In terms of pure power though, Sibson was probably the bigger puncher.
I just feel for one punch that his left hook carried more raw power than any one punch GGG has. Now granted, GGG is a two-fisted puncher with a FAR better arsenal of punches than Sibson, but in terms of simple ONE PUNCH power, I think Sibson hit harder.
Sibsons problems were upstairs, not downstairs. Sibson never believed he could win the big fights. Sibson also did have very heavy hands and his physique suggested he was as strong as GGG if not stronger. If Sibson had Matthew Macklins self-belief, he would have been a very accomplished fighter.
