Simply in order of my inclination to return there:
1. Raja Ampat - profuse life and still (for now) largely unspoiled/undived
2. Komodo - Great macro, plus huge schools of fish in some locations (note: better vis around Sept. when water is cooler than Feb-March when warmer)
3. PNG: Kimbe Bay (and other areas dived by MV FeBrina, e.g., Fathers Reef, Kavieng) - some excellent macro, plus some big stuff - just a great mix of great diving.
4. Galapagos - great big stuff underwater (e.g., dolphins, sea lions, hammerheads), and amazing topside activity walking among the "wild"life
5. Palau - relatively easier access (than above sites), beautiful area with some sharks, good macro, nice soft corals and Jellyfish Lake
6. Maldives - profuse fish life, beautiful soft corals
7. PNG: Milne Bay area (as dived by MV Chertan) - great muck diving
8. PNG: Loloata Resort (near Port Moresby) - world class diving 1/2 hour from the Moresby airport
9. Caymans - very easy access (from U.S.), nice walls, some unusual sites (Tarpon Alley, Stingray City), and lots of turtles
10. Cocos - hammerheads galore
11. Socorro - mantas galore
12. Sea of Cortez - sea lions galore
13. Red Sea (South of Hurgada) - Nice soft corals and exotic fish, but every major dive site is mobbed with divers/liveaboards
14. St. Vincent (but only if I go with Deb Fugitt, who knows where all the critters are!
) - great macro (seahorses, froggies, etc.)
15. Turks & Caicos - very easy access (from U.S.), and surprisingly good diving
Places I never plan to go again (at least for diving):
1. Florida Keys (Bimini and Turks & Caicos are almost as easily accessible, and far better diving)
2. Roatan (totally "fished out" - why go there, when you could easily go to the Caymans or Belize instead?)