Well, I'm really new to the Cichlid world, but I've done huge amounts of reading and looking at species pics.
I'd have to say as far as big guys it would be and albino oscar for sure. If not that, then I'd say my Sevs are a close second
On a medium/large-ish note, I'd say Firemouths, Yellow Labs or Cons
on a medium/small-ish scale I'd say Brichardi
and a small one would be a well colored up GBR.
........So much for picking just one huh