certified for 30 years
logged dives??? who counts anymore
my job took me to the islands

dove 'em a bunch
(I've dove GITMO....)
give me a choice as u describe....well I'd narrow it down to Cayman and Coz ... from there, twixt the 2, it gets tuff. It becomes very wx dependent and if you can predict that you are better than 99.999% out there.
If you want to do a self paced shore dive ... Cayman has better options.
Want a drift dive ..... Coz.
Doing the excursion options....it's a push.
Want a wall again, a push. .. both have great dives for a wall .... but Coz will always be a drift dive. The currents can RIP. Either way, it is a boat trip.
But any day of the week ... weather can rule....
It all depends on the dive op' and where they take you. In Cayman and Coz the common & easy to reach sites are pretty decent. Eastern islands, the easy sites tend to be dull & you don't usually get to the 'good' places unless you have more time. And trust me, in Cayman and Coz if you are staaying at a dedicated dive resort for a week of hard diving, they will take you to the GOOD places after they know you are competent - aka, not a coral buster cuz of no bou' control & not dangerous on the wall cuz of over weight.
Think about it. A dive master has a couple of dives to get familiar with you one way....and u are doing 1 trip from the ship....
But I prefer to go west to Coz or Cayman for a cruise if I'm only gonna get a couple of dives....and when I want to dive, the options are wider cuz you have time to explore. Mixing a cruise and a dive means compromise....