I've dived with whitetip reefsharsk, blacktip reefsharks, grey reefsharks, nurse sharks, leopard sharks, whale sharks, and bullsharks. The whale sharks are definitely in a league of their own, but nurse sharks were definitely some of the most interesting, as they don't seem to mind being very close, close enough to touch, and there's not much risk of an unprovoked attack, so nice big shark, very close, with low risk is definitely a nice experience. Mind you there was shark feeding in the area(at one particular resort), so these nurse sharks were very used to being close to divers.
I definitely want to see hammerheads(the one hammerhead possibility dive I did was a bust), wobbegongs, angelsharks and dogfish though(especially dogfish should be a nice experience, but unfortunately it's mainly cold water diving, and/or too deep for recreational diving).