I've freedove all three.
Belize had stingrays and nurse sharks to freedive with, but Utila was the best witht he whale sharks. Roatan wasn't bad because there were nice reefs right off shore to freedive on, where the other two needed a boat to get out to the reef.
If Will is opening up a place I would love to come down- in a couple of years when my kids are bigger.
Beware the mighty sand fly- they feasted upon my flesh in a big way when I was down there.
Jon