Like the others have said, most soft corals if not all of them will do well. If you decide to get Duncan coral you can feed it mysis shrimp once and a while and it will help it grow. My duncan has quadrupled in size in the 9 months I've had it with a weekly feeding. Going from two heads to eight.
55 gallon reef mj 400 circulation setting ~500gph and hydor 600. Diy 3" dia. 24" tall stand alone skimmer powered by 90gph power head(needs to be redesigned to allow adjusting). 3 Kenya trees and one duncan coral. Two Occ. Clowns, black clown goby, sleeper banded goby, 3 Cardinals, convict tang, pistol shrimp, 2 blue leg hermits, 2 red leg hermits, 1 zebra hermit remaining, 3 astreas and 3 nassarius snails and a conch. Diy canopy w/ led and t5 ho 14k bulbs. Diy stand housing a 55 gallon sump where the heater and skimmer are located. Simple and cheaply done tank.