If you have clowns, go with an anemone that they will host. I'm not sure if they host ALL anemones, but I could be wrong. My vote is for the BTA they're nice and colorful and can expand their tentacles like the other kinds or "bubble up."
Here's the problem with carpets. Your going to need a sand bed for them. They are found off the reefs edges where it's mostly sand. They dig there feet deep in the sand looking for a rock to grasp onto. So if u don't have a decent size sand bed they can be hard to keep when they get bigger.