Hey Nate! Good to hear from you.
If you're interested in strictly scuba, Bonaire is world class. You can walk right out of your hotel, onto the beach and walk right into the reef. Shore diving is all over the island. Other then scuba diving, you can bike around the whole island.
Cayman has more to do on the island. The diving is all by boat, but is certainly very good
So if you're interested in just scuba - go Bonaire. If you also like some of the more tourist type activities in the Caribean, go Cayman.
Let me know how it goes!
Mark