No statistics are kept AFAIK so it's pretty well impossible to answer your question. There are 700 islands in the Bahamas archipelago covering a huge area so I think, statistically it will vary depending on where you intend to cruise. I spend a good part of the year on one of them (Abaco) which is fairly close to the Florida coast (190 crow-miles) and reply from this perspective.
I would say a ratio of 60/40 in favour of power in and around the 'hub of Abaco.' The waters are fairly shallow, which may deter some sailboaters with long keels. Further south in the Bahamas chain I would guess that there might be more sail boats than power as it is more remote and offers fewer opportunities for re-fueling. All of it is extremely beautiful.
I'd agree with that assessment. The western part of the Bahamas gets a lot of power boats over from Florida and there is already an established local fishing charter fleet; as you move across the Bank east towards Nassau they thin out and you see more sail boats. Once you get south to the Exumas and the Out Islands it is predominantly sail.
All of it is beautiful.