I have been to both. First let me tell you that you can not really compare them. Diving Roatan is mostly boat diving and wall diving. It has a bit of current that makes it nice for drifting. Lots of small fish with the some nice grouper. Bon aire is a beach diving paradise. You rent a truck and dive anywhere you want. Boat diving only gets in the way of relaxing. You get to dive and dive and dive. You also get to use nitrox for free in Bonaire. We did over 60 dives in 15 days with out even trying. Lots of small tropicals and lots of sea turtle, eagle rays and tarpon. Night dives with tarpon is a very neat experience. You light up reef fish the tarpon eat the fish in a second flat. Both are totally different with their own qualitys. Do them both you will not regret it.