I did a lot of starfish research a year and a bit back. This is what I recall through reading and speaking to experienced folks. Might not be 100% accurate, but I'm pretty sure I'm remembering properly...
Sand sifting stars will kill everything in your sand bed then die, they're voracious eaters. They also have potential to disturb your rockwork as they will hunt the bottom of the tank along the base of the rocks.
Serpent and brittle stars are fun and very mobile but they do look serpent like and can get big. They're easy to take care, tolerate differing parameters, and are a pet in their own right. A good general rule of thumb for these guys is to avoid the green ones (they hunt your livestock). If you do an online search you can see some vids of them coming out at feeding time, some to the extent that they can pretty much be hand fed. I recently adopted one of these with no legs and am hoping to get it back up and crawling.
Red and Blue linkias are more traditional starfish. Blues are harder to maintain than reds. They need to be in a well established and stable tank, where they'll prowl the live rock and glass. If you drop them into a young (less than a year) tank their chance of survival is practically nil - they may survive a month or two but then will start to die and fragment. They're not very active but nice to look at. I skipped on a blue (too risky) and dropped a red into my mixed reef. My parameters are very stable, I feed well, supplemented with phytoplankton, and I seed copepods every once in a while. They also eat astrina stars. Its been in just over a year and it seems to be doing well. Mind you, it hasn't grown much but it hasn't shrunk either. I may have gotten lucky or it may start dying tomorrow. In a well established tank its still a crap shoot with them.
I also have a tiger pistol shrimp and 2 cleaner shrimp in the tank and there's never been a worry. If you have a harlequin shrimp its a problem, as they exclusively eat starfish.
I did have an emerald crab that would nibble on corals a bit, when I caught him nibbling on the star he was banished to the sump.
Hope this helps.