The Mandarin fish is a beauty. If I had the dedication for a tank. I would definitely have one of these.
Lion Fish being predators however glide all over the tank majestically and you don't have to go looking for them in the nooks and crannies. I remember dear Grandpa's talk where he had two of them. They always seemed to be performing some kind of Circ du Soleil surreal thing.
Maroon clowns are a lot of fun, especially if you have a mated pair. Mine lasted about 10 years. I recommend tank-raised. They go well in a bubble-tipped anemone, which is pretty much the only one that you can get that is captivity propagated.
Purple tangs are hardy and beautiful, if you can find a decent specimen.