Best Corals for a beginner?

[Squidmotron]

For trying your first SPS, I recommend any Montipora. They are colorful, easy, and I honestly couldn't kill mine at all in the beginning no matter how much I screwed up.

The problem with GSP and Xenia is that they can easily become out of control weeds that dominate your tank. If you choose these, I recommend placing in an isolated rock structure that you don't mind gets covered by them and won't easily spread to the rest of the system. I also have GSP growing up the side of my overflow and I trim it very carefully back with a razor blade to keep it from reaching the rocks.

Honestly, I'm not sure I any photosynthetic corals are really "difficult", and I always wonder about the way we classify these things. Some corals have requirements that you have to know, understand, and provide things for (i.e., sufficient lighting). For some, it may be best if you have experience and a mature tank. But they are not "difficult" if you prepare yourself and have the knowledge.

[Reeferz412]

Mushrooms (discosoma), leathers, zoas are pretty straightforward and easy to care for, caulastrea, montipora cap is also pretty bulletproof with the right lighting, clove polyps, sympodium, briareum, anthelia... just to name a few. Stock up on what I mentioned above and you will have a low maintenance tank with a pretty large variety.