If I recall, the footprint of the 26 gallon is essentially the same as the 20 high, just taller and a little wider at the widest point of the bowfront. I would not suggest keeping 2 pairs of dwarf cichlids in this tank. Angelfish typically coexist well with rams... depending on what else is in the tank, you might be able to get away with a single angel. Keep in mind that, although it takes years, adult angelfish can grow quite large and you may want to consider a larger tank. Of course, you'll have years to figure that out assuming you start with a juvenile.