If you have stock lighting and everything, LPS and zoas are your best bet. You can also go softie adn zoa. I wouldnt mix LPS< SPS< SOFTIE and so on, as you have a small tank. Dont go SPS at all, as the lights will never support it. Dont get anemones, as they need lots of light too, and other reasons they arent good for a reef. Zoas, mushrooms, and a few soft corals would look REALLY great. I ahve a 24, and have added a chiller, MH, extra powerheads, adn have more coral than space. Good luck.