It's been years since I dove Grand Cayman, but I did have a couple favorites. The shore dives at Cobalt Coast were great, as were the ones at the Turtle Farm. Hepps Pipeline was a great boat dive where you could see the bottom at 100' from the surface. It had some canyons to swim through. Folks who have been there recently can tell you ithese spots are sill good. And of course, the stingray feeding dive is just pure fun.