When I did my cave training, I asked around, and I searched the discussion boards for all the threads asking for recommendations. I learned an important thing--different people are looking for different things from their instructors. I saw, for example, that one instructor was recommended for being a total hard butt. Several people praised him for his ability to swear at you articulately through his regulator. I decided I did not want that. I went instead with someone who had high standards and was able to require that I meet those standards without feeling the need to humiliate me.
I'm not real big on humiliation either. I've cussed at one student ever. He tried very hard to kill both of us in the cave, and almost managed to kill himself. When we got to the surface, I did cuss at him. I kinda feel bad about it. A little. But he had it coming. I am embarrassed that Jill Heinerth was standing next to me for the exchange.