When I was certified Full Cave in 1990 I looked for an instructor around the Atlanta area and sat in on some classes and found one with a unique perspective. He believed that if you're going to be diving in a cave that you should be Full Cave trained. He didn't believe in getting some training, then going cave diving on your own and then getting more training and cave dive on your own some more. He felt you should have all the tools at hand every time you went in a cave. But he also didn't think getting to Full Cave in a week was responsible.
The approach he took was to have classes here in Atlanta during the week in the evenings and then dive every weekend. It meant quite a commitment and really, you had to live within a day's drive of N Florida to do it, but it made sense and so I set aside the time. Since I didn't have to be in Florida all week I didn't have to take off work at all.
We had a group of six student and two assistants and the classes were intensive as well as the diving. Over that month we did 22 dives in as many different conditions as possible. He was an NACD and an NSS-CDS instructor, so you could choose either certification card. I chose NACD. There was no GUE and back then the fight was between the NACD and the CDS. But it was still over DIR etc.
Every time I get in the water I am thankful to have met that instructor. I was fortunate to meet and learn from two great guys, my cavern and cave instructors. The cavern instructor was a resident instructor at Ginnie and he was excellent, but when I was ready to take up cave, I listened to prospective instructors' philosophies and chose one based on his approach.
Taking your time to absorb the skills yet doing it all at once made sense to me. I don't know if there's an equivalent approach out there anymore (both are retired from teaching), but the advice to choose the instructor and not the agency is good.
Having said that, I'm very impressed by the reports I hear from divers who used GUE cave instructors for their cave instruction. And there are good and bad instructors everywhere, so meet him/her, talk to him and get input from people who have learned from him. If possible, sit in on a class.
I've seen some terrible instructors out there and since your life is literally in their hands both during the course and in the approach that he transmits to you during instruction, I'd take my time choosing and get as much input on the instructor as possible before signing up. The habits you learn during training will color your dive experience forever.