Key West is a great port, Nassau has the Atlantis and Cabbage Beach, and I haven't been to Freeport in years, but people have written some bad reviews-I used to love Freeport, even better than Nassau. However, as I said it has been years since I've been. Lucaya was a beautiful development there, at one time.
Ocho Rios you have Dunn's River Falls, which is a MUST if you go. Grand Cayman you have Stingray City and Seven Mile Beach, plus some really good snorkeling and shopping. And Cozumel you already know about.
That's a tough choice!