Personally, I really don't like hermit crabs. When I had them they were just bullies trying to eat all the snails, even when provided with extra shells.

Snails I really like are: caribbean nerite, margaritas, nassarius, ceriths, and turbos. I also keep cowries, but I believe that may be out of the norm.

Crabs: emerald and strawberry crabs

Misc: I love blennies. They are great little eaters