Schnelly, Johnson, Davis, Erickson, also rans. I give Butch nod over Erickson because of the recruiting. Once Butch's boys were gone Erickson was done. Also, Erickson was in charge when the Pell Grant scandal(I do blame the administration much more that Him). This is Miami so anyone who wants Butch behind Erickson has valid point -- Titles matter. Howard had a NCAA issue also but going from nothing to NC makes up for it.
If the question is which one leaving hurt the most, it is Butch. His eye for players and coaching talent was greater than even Howard. His field coaching shortcomings would have cost us some titles his players could have won but we probably win at least one every three years if he had stayed. If Butch was still here there is no way the talent would have dropped this low. Saban might have still revived Bama but not like today. Butch would have gotten at least 4 rings by now. Keep in mind how clean a program he ran and players he recruited were. Howard and JJ, better coaches, but both had problems with troubles.