I can't pick just one. I like favias, chalices, euphyllia, acans, micros, platys, scolys, fungia, duncans, blastos, etc. LPS in general is my favorite.
Yeah this is a really tough question: Blastos, Chalices and Acans are on top but out of everything in my tank the hammer and torch has been my favorites that have survived everything. Most people are drawn to them with their bright colors and movement. I give them the edge!
For me its Blastos! They are my favorite LPS but they are also the LPS that ticks me off the most sometimes. Ive had over 35+ color morphs, but out of nowhere random ones will just start receeding whether they are new additions or have been in my tank for over a year+.