I have also gone with Pro Divers at St. Kitts and had a lovely time. They took us to an area with an underwater vent, and another area with a lot of crusing sharks. Was a great time.
As for Tortola, I've only been there once, but Blue Water Divers BVI was excellent. I saw my first reef squids with them! I can't say which is better, honestly I would dive both 😁