If your only concern about Marina Cay is the ferry, I really wouldn't worry about it. You can pick a spot in the mooring field where you are not on the edges and the ferry won't go by you so close. We've never found that to be a problem.

Each location has its attractions though. CGB has one less for us with Green VI glass blowing moving to Bitter End. We really loved stopping to check them out and see what they had and would typically bring something home with us.

If we could only do one, I'd probably go with Marina Cay as we love snorkeling Diamond Reef.