dont keep xenia (or blue xenia), clove polyp , gsp. They encrust rock, which is why its hard to get rid of them. Frogspawn, hammer etc may grow fast, but if you want, its relatively easy to frag them off. They grow big, which is the main reason I would hesitate to keep them , since I dont want to relocate corals in my tank for several years, and I also want space for other things.
Zoa's are good choice, can lords are good choice, there are some cyphastrea and leptoseris that will be good. Remember, other than your isolated island, you can also your rockscape the kinda segregate the corals, they all avoid shaded places, so wherever you have two rock faces separated by a shaded place, they are perfect to keep separate fast growing corals.
Another point to consider is that you can keep some smaller polyp softies, like some zoa or cloves or some monties that are encrusting on the base , while grow some branching hard corals on the same rock, its very much like you have a big tree (branching coral) and grass/shrubs in the ground (encrusting corals, cloves/zoas). This work out becuase the shade produced by the branching corals inhibit the encrusting coral to grow towards its base and encrusting itself. You have to rememver to add the branching coral first, and then introduce the encrusting one later, and the whole thing needs to be done in a way that considers those corals growth rates.
Anyway.. dont want to side track the thread

, but I think rockscaping and coral placement is a very involved thing and I was only able to understand some aspects of it after couple of years of reef keeping when I realized how individual corals grow and how flow, light & rockscape controls their direction of growth/sweeper tentacles etc.