There are a ton of threads that compare the phases.
Having stayed in both VG and BV, I personally prefer BV. The VG units are older and showing their age, although that shouldn't be an issue now after the hurricane. To me, the major downside is that VG is across the street from the main resort. It has its dedicated pool, which is nice and less crowded than the main pool, however there is no bar and no poolside service. That IMO is a major drawback because there are few things nicer than ordering a Painkiller while you're enjoying the sunshine. Also, if you want to use any of the resort facililties (e.g. gym, hot tub, main pool, beach, on-site restaurants), you have to either drive over or walk across the street and up a really steep hill when you return. Major calf workout. In theory, you can hail an iguana, but they aren't always around when you need one.
BV is up a short hill from the main resort, but still a part of the main resort, so I like its location a lot. And the units are super nice. The 2 bdrm lofts are really large and plenty of space for 6-8 people. The biggest drawback is that there's no close parking like VG, and it isn't ideal to have to haul snorkeling equipment and coolers up that hill.
I've never stayed in CV, but it has the same issue with parking. The newest phase, Sunset something, is ground level really close to the pool. However, the Sunset phase wasn't built to be a timeshare but rather renovated from hotel rooms, so I'm not sure if the layout is as nice as the units that were built to be timeshares. Sunset may also have noise issues from the pool.
If you get assigned a loft, then I think you'll be very happy. Just make sure that you indicate that you'll be bringing 8 guests or they could change your room.
I think it boils down to this: If you crave privacy, VG is the place to be. If you want to enjoy on-site amenities, then the other phases are more convenient.
