Both of those places have a big spread in quality of dive sites so don’t judge them by two dives in each. I’ve been back to Roatan a few times and it never fails to please.
Roatan is one of the must do dives in the Carribean, the others being Bonaire, Cayman and Cozumel.
Did Belize once and it was windy so dive sites were limited to the lee side of the islands and with the seas kicked up viz was down but we still had some great dives. Enjoy