Well there are quite a few options, Angels obviously being the most common
there are many smaller cichlids such as Bolivian Rams, German Rams, Kribensis, Keyhole cichlids, Cockatoo Dwarfs, etc
as well as larger cichlids like Festivums, Severum, firemouths, convicts and blue acaras
IMO you would be fine with a pair of maybe two or three species of the smaller cichlids or a small group of the a single species
and for the larger types you could go with a single pair of one species, or two or three fish from across the species