I recommend a favia or favites, that way when it gets big and if you don't like it you can actually sell it. Favias are easy to keep, will do good under your light, are colorful and awesome. Plus you can feed it at night once a week if you like doing that but you don't have to.
Our first one was a Colt Coral and I have loved it! It is really easy, grows really fast, and still has that "classic coral" look that SPS has. I know its not the "fanciest" of corals, but it has been a lot of fun to look back at my first pictures of it and see how much it has grown good luck and enjoy! let us know what you get! Happy Birthday!