Nope, I love them all.
Gorgonians - great swaying movement and just makes any tank feel like a reef
Euphyllia/Fimbriaphyllia - great movement
Plates - super cool, super vibrant, spruces up your sand bed
Zoas - colors, colors, colors
RFAs - see above
BTAs - movement, colors, and cheeky to boot
Montis - great growth patterns across the board
Stylos/birdsnests/anacropora - nice sticks, easy to grow
Pavona - when they get to colony size, so impressive
Trachys - meaty, cool corals that get more and more impressive as they grow
Clove polyps - yes, even cloves are great, giving movement and color
Toadstools/leathers - size, presence, now that I have them, seems like a staple
Pink Nepthea - elegance and grace in a coral
Caulastrea - colonies have such a great appearance.
Pectinia - super interesting growth patterns, vibrant colors
Acans - meaty and colorful
Blastos - see above
Alveopora/gonis - like underwater flowers, great movement
GSP - everyone that sees your tank will be immediately drawn to this expert coral
Xenia - yes, even xenia. Mesmerizing movement.
So many more. How could I pick one?