Pygmy will be happier at that size tank, but in general coral beauties are actually much more likely to be the "chiller" option. Cherubs have a lot of spunk. I'd stay away from leopards or lyretails personally, but a smaller anthias like resplendent or Ignatus or dispar could workinstead of the coral beauty should i go with a pygmy (cherub Angelfish instead since they are smaller yet or are those fish to agressive?