All of those places offer decent scuba diving. If it were me, I would leave out Grand Cayman because of the high fees for diving, the damage done by the hurricanes and, unless you are on the other side of the island, the dive sites can have as many as 200-300 divers from the cruise ships. Plus ...sharks are very rare around Grand Cayman. Maybe.. just maybe a nurse shark..which is not really a shark in my mental dictionary.
The other places are all reasonably priced. I would not expect to be able to do the best diving at any of the locations - when they find that you are a cruise ship person (and they will), you automatically get placed in a beginners cattle boat regardless of how many C cards you have or even if your name is Coustou. The only way around this is if you have a personal relationship with the dive operators from years of diving.
Book the trips your self and save a major bundle. Booking through the cruise line will cost you 2-3 times as much. Yes, you are guaranteed that they will wait for you in the event of a delay..but you are on vacation looking for adventure anyway right? he he! No seriously, you will be back in time. Save the money and dive for several days.