Assyria and Indonesia are two civs I am excited to get because I have felt for a long time they were conspicuous in their absence. Not being much of a warmonger, I can't see myself actually playing as Assyria very often, but I am quite pleased to finally have them in.
Brazil and the Shoshone I am also very excited about because of the precedent they set. Thus far, the New World has, at best, consisted of: The Big Three pre-Columbian Civilizations (Aztec - Maya - Inca), America, token Native American civ. That we're finally getting a second (non-Big Three) Native American civ, and a second post-colonial nation as well, is very encouraging.
Despite the high levels of snark about the Zulu, I will continue to defend their inclusion. I didn't want them back because I thought they'd be given an intriguing play-style that would make them my favorite civ ever. I wanted them back because I've been playing the Civ series since it only had one game, and it doesn't fully feel like Civ to me without Shaka. That I'm not voting for them in the poll as my "favorite new civ" is no reflection on how much I wanted them back or how pleased I am that they finally are back.
Portugal needed to come back*, but I find myself unable to muster any excitement about Poland or Venice. It's not that I don't think they're deserving, but the ratio of European civs to any other group is bad enough as it is. I do want Poland and Venice in, but I want other cultures in more. I would have been more than happy to trade Poland and Venice for the Khmer and an additional Native (North or South) American civ. Morocco leaves me underwhelmed as well for the same reason. I won't complain about getting a new African civ. But the fact that the new African civ is also a Middle Eastern civ with ties to Europe does make the continued ignoring of civs like the Benin, Ashanti, Great Zimbabwe, and (except for a City-State) Kongo all the more blatant to me. I'd have liked to have seen one of them added, not instead of Morocco, but at least ahead of or even alongside Morocco.
*ETA: Though I find the implementation a bit odd. I understand that Trade Routes are one of the big new mechanics, but did we need two European naval trading civs in one expansion? It's a shame they feel so obligated to make new civs tie in to new mechanics so strongly, because I think Portugal should have had an exploration focus rather than explicitly a trading one. And it should have had a different leader. My face still hurts from the epic palming it received when they revealed Maria the Token Chick.