As Cynde pointed out, Den Lamen and Sand Dollar share the same dive shop Bonaire Dive and Adventure (BDA) which is probably the best value for nitrox on the island as they offer unlimited nitrox tanks and weights for $105 for 6 days (not necessarily consecutive) They have a good pier set up with easy tank access and a walk in gear locker, along with smaller individual lockers (which you can use to squirrel away tanks for night dives and create your own 24/7 tank access). We've used them several times.
We have not stayed at Sand Dollar, but we stayed at Den Lamen in February and it is nice. As mentioned, it is brand new, well appointed and right on the water. We used to stay at the Yachtclub apartments, but now that we tried Den Lamen, we will be staying there in the future including two weeks coming up next January.
While we have not stayed with Buddys, we have dove with them a couple of times and they are very good as well. It is located only a couple of hundred yards north of Den Lamen/SD and now that they have taken over Lions Inn and Bon Bini Divers, their dock setup is as nice as it gets with a covered area with convenient lockers, an enclosed area with protected stair access into the water and 24/7 tank availability (although you have to lug the tanks up the stairs if you are going off site after hours) Buddys also has a neat drive through tank station open 8 to 5 which is very nice.
The dive sites at these locations are very similar and very good. In fact, Bari reef in front of Den Lamen/SD has had the most species identified on it of any dive site in the Caribbean according to Project REEF. There are approximately five designated dive sites which can be dove from either SD or Buddys pier and they are both perfect for night dives as well.
As mentioned these resorts are all located north of Kralendijk and several miles from the airport so there is no airplane noise.