Not only is this an excellent question, but your choice will color your entire cave diving experience. So do your homework. Find someone that not only does a good job of teaching, but does it with a style that is comfortable for you. Talk to everyone you can. Ask them all kinds of questions about their training and their instructors. But, since almost everyone only takes a single course from one instructor, it can be difficult for them to be objective, so you also have to be wary of TOO glowing a report. You should also contact the instructors that you are thinking about. You can see a listing of all NSS-CDS instructors on the NSS – CDS Cave Training Website.