Buddha View Diving Resort, Koh Tao, Thailand
I did my dive master training with Buddha View back in December 2011. It is quite a large operator, with lots of students and fun divers. This leads to an experience that is not very personalized - the boats are quite large (with dozens of divers on each trip), and the divemasters are often just so busy that it is difficult for them to spend much time with each customer. All this said, it is still very professional - decent gear, decent boat, decent training as well for courses. There are basic accommodations and food on site, although there are other great (and probably better) places to stay and eat along the adjacent beach. Make sure to try to Burmese curry at the little restaurant next door :) However, Buddha View does have a GREAT bar right on the water, which is very fun after a good day of diving.