Hi,

I own a unit at Divi and have visited Belair many years ago. If these are your 2 options, Divi by far, especially for 4 maybe 5 folks in a two bedroom, as the Belair second bedroom is just big enough for the bed. I'm guessing you will be getting a time-share unit at Divi and they are large.
These two resorts, next door to each other, are a bit remote for many on this site as they like the Simpson Bay and Maho areas. A rental car cures that with some extra driving and the fun of finding a parking space.
The beach has calm and clear water with no drop off to speak off and you have the view of Saba most days and the fun of seeing the cruise ships coming and going.
If it was just one couple, I'd say it would be a toss up.