Centrals, most dive centers in Kenting are awful. I mean really, truly horrible.
I usually use Dive New World.
墾丁帶福新樂園潛水訓練中心 Dive New World | PADI 5 Star IDC PADI 5星教練發展中心
I only go there a couple times a year now that I live up north, but they have always been professional, safety-oriented, respectful of the ocean environment, etc. They are capable of supporting tech diving as well as recreational, although deco diving, gases, etc., would need advance preparation.
I also refer visiting recreational divers to CT Divers, run by a nice couple of professional, responsible, friendly and eco-friendly divers.
About Us
At New World, Yi-Nen's English is limited, and I doubt he speaks Cantonese. But he is a nice guy and a serious tech diver who brings to Kenting a level of professionalism that's usually lacking. Xiao G speaks pretty good English, and she seemed to be managing the place most of the time when I was last there. Also a tech diver, a serious professional, etc. Again, I doubt that she speaks Cantonese. (I haven't been there for a year, so not sure they're both still there. Other staff members tend to be shorter-term, like DM candidates, newly-certified instructors, etc.)
At CT, both Carrie and Tony (their English nicknames: both are Taiwanese) speak excellent English.
New World has its own dorm at the dive shop, with beds (in a room of ~10) for nt$500ish. The shop is near a 7-11, and on the main road, and doesn't have much else nearby. You can rent an electric scooter or take a taxi. Honestly, though, Kenting Town isn't much of an attraction …
Carrie and Tony will put you up in a hostel in Hengchun, the small city about 15 or 20 minutes away, unless you have chosen another place to stay.
New World's boat was not ultra-comfortable last time I was there, but they at least were focused on good dives rather than crowding lots of suckers into cattle-boat dives with 40-minute surface intervals, like much of the competition.
Not sure whose boat CT uses. That's worth asking about, because as much as I like and respect them both, on the boat, it is the captain who has all the power.
I have in the past upset some people when commenting on the Taiwanese dive scene, so I'll end this post here and do the rest by private message.