The BVI is nice to sail in - quite easy and lots of things to see and places to anchor. The big players are SunSail and Moorings, and then many other smaller charter companies ranging from large operations with many boats to 1-2 ship operators.
Do you want a single or multi-hull? What size and what length? What price category (pricey but with lots of beeps-bells-and-whistles or less expensive)? I just looked at many charter/ex-charter boats in the BVI two weeks ago and got a good feel for the charter companies and their maintenance methods.
The BVI is a wonderful place to sail in - you'll love it.