Depends on what you want to do. Coz is more of a vacation where you dive some...you do a 2 tank dive in the morning and whatever you like the rest of the day. There is a little shore diving but not much, you are usually stuck at the resort you are at...if it has a beach. You can at times do afternoon/night dives but at a cost. Unlike Bonaire that is a dive vacation, you can dive as much as you like, whenever you like.
Also the dives themselves are different. Coz is almost all drift diving, you jump off the boat, ride the current with the group and get back on the boat when you are done. Dive times are somewhat limited, 45-60 minutes. Photography is somewhat limited in Coz, esp macro. You are traveling with the group so you don't have time to stop and shoot as you like, you have to do a quick snap and haul to catch up with the group.
Bottom line is if all you want to do is a couple of dives per day, don't mind staying with a group and having your bottom time limited Coz is nice. If you want to do a lot of bottom time, night dives or want to spend a lot of time with an UW camera, Bonaire is a much better choice.