Ancelotti
It takes a world class manager to know another. People here have already made their minds up about Pep, they then try to rationalize every success he has to fit their narrative. But if you were really interested in the impact he has on his teams, read up on his team's statistics, his training methods , his ideas, his philosophy, look at what players and coaches say about his obsession with the slightest details. The guy is an amazing manager, and whether or not you agree he's the best, there's no way you can deny he's one of the best.