Who have you got? I'll take Manny Steward at #1. He trained Lewis and Klitschko and turned them into dominant champions, even if the latter was a remarkably boring fighter. He even trained a young Fury and James Toney. Not sure how the rest of my list would look
Nacho Beristain has been the best during this time. I’m not sure who’s particularly close outside of Steward off the top of my head.
Bill Miller trained James Toney, and Emmanuel Stewart. The best trainers, the guys that do the actual gym work and teaching, are people you have never heard of. Almost every name that will be mentioned in this thread will be the name of the guy you see in the ring. They are generally not the same people.