I would agree on the earlier recommendations for shark junction. It is a Bahama signature dive as there are very few opportunities to swim with the reef sharks on a regular basis, this is one and it is a rush.
I have not dove GB since 2002, so I can't comment on current condition of the Sea Star. We dove it just months after it was sunk, it was intact and it was a fun dive. From the previous post, it sounds like the hurricane tore it apart, but that will just make the dive area larger. I dove Theo's wreck too, but I don't know how it fared either. I would also second the tunnels and caves. I remember that was a fun dive.
As far as operators, I have dove with Xanadu and Caribbean Divers. Xanadu was bigger, but had boat issues (and probably money issues) but ran the best shark feeding dive known. Caribbean was a two man operation and I don't know if they survived the hurricane. They were small, did not offer nitrox, catered to cruise ships (they would divert dives to shallow sites when they had a boat full of resort divers or students), but otherwise, a blast to dive with. I have heard nothing but good comments from divers who have used Grand Bahama divers, although I have not dove with them.
Where are you staying in GB? Are you staying in Freeport or Port Lucaya? I would like to hear how from anyone who has been there recently how these areas have recovered from the hurricane as I heard GB took a direct hit. GB was one of our favorite dive destinations because of the combination of good vis, sharks, casinos and short plane ride.