Uninhabited Conception Island is our favorite Bahamas location. The diving there is excellent. On the southwest side of the island there is a series of dive moorings on the drop off. The top of the wall is marked by large coral outcroppings with tops at 50' with wide sand chutes at 70' between them. These moorings are used (and maintained) by dive boats from Stella Maris (Long Island) and the Nekton Rorqual liveaboard. There is also snorkeling and shallow diving in the West Bay anchorage. We often do night dives off the boat there.
San Salvador is a north-south island with a drop-off on the west (leeward) side. There are many dive moorings along this wall used by the dive operation at Riding Rock Inn. At our first visit they were also being used by boats from the Club Med but this has since closed. Hopefully, the moorings will continue to be maintained.
We have also dived at a few locations in the Exumas (Warderick Wells, Rocky Dundas, George Town, etc.) and in the Abacos. It's a little harder for us at these locations because the best sites are probably on the windward side. There are also few or no maintained dive moorings.