I would recommend Flamingo Divers and could not possibly recommend them more highly. We came here to research the best dive outfit too and went with FD after reading a bunch of reviews on their small dive boats. We were not led astray!! They are a MUCH smaller outfit than Provo or Caicos Adventures. The largest dive group you'll have is 8 people. Most of our dives were me, my boyfriend, and one other diver.
Mickey and Jane run the dive shop and conduct all the dives together. They are very familiar with the area and just all 'round great people. We went diving five days; saw whales underwater while diving on two dives. They tend to take off earlier than the other shops.
Most dive ops leave from the same place. From our perspective, we were so happy when we sat on our boat with three divers and two DMs and passed by Provo and CA docks, each of which had huge groups on their boats. The day we dove with whales, Provo was also there in the area--but they didn't see the whales until further in the dive and luckily the area was so large and the whales were so large that we never saw them under water. That same day, the CA boat blew right by the area altogether.
CA and Provo may well be awesome outfits, something I wouldn't know as we didn't dive with them. The only thing I can compare is the number of divers and in that respect, if you are looking for a smaller, more intimate outfit, I'd suggest Flamingo.
[I'm a relatively new diver--just finished dive 37--so my dive ops experience isn't that varied but with that said, this op just captured the right feel and level of friendliness. I should also mention that my incredibly expensive awesome reg (heh) went into free flow during one of the dives and Mickey was "ON IT" within seconds, had me breathing on his reg, turned my air off while he fixed it, and back on my reg within 2 minutes. Terrifying experience but handled quickly and professionally....]