I liked the soundtrack of this expansion a lot. It is hard to pick favorites, but I guess I'd go with Poland, it is beautiful! Brazil's also awesome, Portugal too. Assyria is another great one, kind of cyclical and reminds me of a [] for some reason, but it is epic! Gotta love Indonesia's misterious track too, also liked the Shoshones' one.
Didn't really like the Zulus', Venice's and Morocco's. I have to say I like to listen to Morocco's War theme sometimes, but it is kind of bland. I disliked the Venetian one, sort of... generic? Something's missing there. And the Zulus have a nice song, but it isn't something I'd listen on my ipod (yes, I add civ songs to my songbank, judge me).