1+If those are you're choices then Salvini's are the only choice. Rams are a waste, Firemouths and Geo's are too docile (boring) and some Dempsey's have potential to outgrow a 55. Salvini's are entertaining fish and very beautiful. There has got to be alot of other nice choices out there if you do your reasearch...might have to mail-order some but worth it to have something different,cool and interesting...???
Im a huge fan of the Salvini. stunning cichlid, especially the females. Id choose them for a 55.
If you do want something different, Id look up Jeff Rapps instock page and see what he has that will work for a 55. He always has some awesome fish. Shoot him an email, he's very helpful.