I like anything Parachromis or Amphilophus, but I'm really starting to like Veija species too. Firemouths have great color and stay small, male Paraguayan Earth-eaters (balzanii) have beautiful bright blue marking and are full of character. Jack Dempseys are one of my favorites, but IDK if the smaller more docile Electric Blue JD will be able to fend off some of the beasts u have.. Even small Devils pack quite a wallop, and I've seen male GT/Gold Saum dominate an entire tank, including Flowerhorns, JDs, Devils, etc.
It's hit or miss....I have housed different species that lived harmoniously and you could have another tank, same size, same species, just different individual specimens, and it could be a disaster. It really depends on the fish's temperament, not the species' temperament; and size too - 1/2 inch can be detrimental to setting your hierarchy.