Babylon is quite a strong civ, but I really like their colors as well. Rome is pretty cool with their royal purple. America's colors fit quite nicely IMO even if it's not a civ I particularly care for. Mongolia always looks like a plague spreading across the map, which seems fitting. Something about the Aztecs seems very fitting in terms of being cultural killers, and same with the Celts and Indonesia for their religion and war emphasis. Egypt also has a bit of royal gold and purple going on. Korea's colors scream science for some reason to me, have no idea why. Maya's colors reflect their love of religion and peace quite well IMO. Polynesia's colors seem to reflect cultural islanders quite well. Russia's colors always seem to reflect their productive and expansive tendencies. Sweden and Venice's colors also seem to reflect what they emphasize.
Super abstract, I know, but I really feel like all those colors work very well for the civs in question.