Earth eaters in general are some of my favorite cichlids to keep.
Beyond looks, I like their social structures, and interaction. For most I had, a group of 5-7 of the same species worked well in a 6ft tank. And if kept in a group, would not be aggressive with other species I would also keep in the tank.

Although most Geophagus would fit nicely into a 6 ft tank, for Acarichthys it seemed too small, once they matured.
The cool water Gymnogeophagus really sparked my interest over the last few years though.

And I found the Geos very similar counterparts, the eartheating species of Central America, to also be of similar temperament, if kept in large groups.