I have never heard of a crab that someone has not had a bad experience with. that being said I personally like (and have in my reef) the scarlet reef hermits, sally lightfoot crab, and emerald crabs. They have never given me problems but that is no gaurantee as many people on this board will tell you horror stories about each of these. Basically it's hit or miss with some of these crabs as yo can always get a bad one.