right now it would have to be cyprichromis leptosoma - a staggeringly beautiful fish (male) and the courtship / spawning is a real event to witness.
Whilst spawning, the male will keep fish much bigger than itself at the other end of the tank, yet outside of spawning they are as peaceful as you could wish for.
As with many other cichlids, they are so much more intelligent and socially complex than you'd expect, a very curious nature that you can observe watch for hours.....