Ahhh, I'm such a noob. Oh well. In my limited experience, I have one 2006 dive that was more special than the others. In the spirit of a countdown, beginning with my third most favorite - the pumpkin carving at Gilboa, more for the SBers there than the temperature, vis, or activity.
Second favorite, would be the dives with Not So Ken when we watched and photographed Ber Rabbit's OW class. For an OW class, they had impressive buoyancy control. The enjoyment here was topside with the excitement they had after their first dives.
Most favorite dive was # 6 in the log. Buddy was a college buddy who encouraged me to dive. Location was Molasses Reef off Key Largo, the Spanish Anchor. The earlier dives that week (all 5 of them) we saw fairly usual stuff (I've been snorkeling for years so it wasn't all new to me - huh, jaded at 5 dives...oh well). We saw a huge Goliath grouper, and a 6 foot shark swam within a few feet of us. Then we posed with for photos with the anchor.