It's funny, how do you define "Best College Coach" ever. Clearly based on results he is there, but the playing field is never even. He is clearly the best program builder ever, clearly one of the top recruiters ever...but given the talent that he has every year does he achieve results that would be befitting of the "best coach ever" mantle.
He starts this season with the top 3 class of 2018 recruits, including the top 2 talents in the next NBA draft. When he loses one of those 3 he can turn to a prior year 5 star Marquis Bolden on his bench. When Trey Jones goes down he can turn and insert a 4 star and #33 player in the class of 2017 Alex O'Connell as a replacement.
What would JB, Buzz, Mike Brey, Bennett or Chris Mack do if they consistently had the talent that K has had? Would the results be much different?
I think K is has built a fantastic program at Duke. Is he the best "coach"? Depends on your definition. Calipari is the same deal, only a bit more obvious as his results haven't compared to K's.