My favorite, John Benner and David Bowie (the swat guy and gunsmith not the rock singer) of the Tactical Defense Institute. I also was a guest instructor for Mas Ayoob's LFI many years ago. His stuff is very good on the legal aspects. John and David teach house clearing at the highest levels.
Some of my friends swore by Clint Smith or John Farnham as well. All are really good