My estimate is based upon the list of this thread:
http://forums.civfanatics.com/showthread.php?t=488701
God Tier: these civs are so good that they can win from almost any kind of starting point, and they are often suitable to win in many different ways.
Ethiopia, the Mayans, Austria, Arabia, Korea, Babylon.
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1st Tier: these civs are in general fairly good, but they are not as good as the God Tier civs.
China, England, Mongolia, Egypt, the Celts, the Incans, France (1 up), Shoshone, Brazil
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2nd Tier: these civs are decent, but they are lackluster compared to the other civs on the higher tiers, or require some luck to get going.
The Netherlands, Russia, Siam, the Aztecs, the Huns, the Iroquois, Rome, Persia, Greece (1 up), Morocco, Poland, Portugal
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3rd Tier: these civs are considered to be not that great but workable.
Germany, America, Carthage, Songhai, Denmark, India, the Ottoman, Assyria, Venice
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4th Tier: these civs are comparably pretty bad.
Byzantium, Sweden, Japan, Polynesia, Indonesia, Zulu
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Dice-roll Tier: way better than God Tier with luck, 3rd~4th tier without luck.
Spain.
The god tier civs for me, did not change, but there are quite some first tier additions.
Reasons for my classifications:
France: The new ability is very powerful especially when you go complete Aesthetics it is 4x the normal Theme bonus for Culture and Tourism in your capital. You will build culture wonders with France anyway, and because most cultural wonders are midgame, you will have a chance to build quite a few of them even on higher difficulties. France is also able to get more culture and social policies than any other civilization. Maybe only rivaled by Poland, by the number of policies.
Shoshone: The Shoshone are very good. The Pathfinder is awesome, and offers you a lot of possibilities in early game. It would be God tier, if you could select the faith bonus with your very first ruin. The way it is now, does not guarantee to get a religion, without building a shrine.
Brazil: Brazil is a great tourism powerhouse, when you manage to get a lot of golden ages, which can be done through great artist burning, as well as with their unique unit. You can even time your great musicians to spawn during your artificial golden ages, to make them stronger aswell. The wood camp finally offers another imporvement for jungles, except trading posts. The special unit has a nice trait, but comes in too late, Although it can be used through the rest of the game and does not become obsolete, except you upgrade to mobile infantry, which you do not have to.
Greece: The control of the World Congress and easier/earlier diplo victory makes Greece better than before. The lack of gold for CS in early game is also of less sgignificance for Greece, because it can maintain the ally status far longer than any other civ. While oponening Patronage is a must for Greece, you will also get extra delegates for building the Forbidden Palace, which is also unlocked by the patronage tree.
Morocco: The Kasbah is nice, but does not let you build anything else on the tile unlike the Petra. The unique unit is decent and the Trade bonus let other players prefer your cities for their trade routes. This civ is missing some flavor, like the Kasbah should be a building in the city, which gives you the bonus for all tiles of the city, like the Petra, but I guess that would have been too powerful. Now they are just a mediocre civ.
Poland: Poland is very good for culture and getting a lot of social policies, but without a mayor tourism bonus, it is not such a significant civilization for a culture victory.
Portugal: The Feitorias are awesome, while the pure gold bonus on different resources at trade routes does not seem to be much of a difference. The Nao is only a mediocre unique unit and is not as powerful as it should be. Portugal is only good on water maps, Feitorias and the Nao are almost useless on Pangea or any other land based maps.
Assyria: Assyria has a great unique unit, but the unique ability is situational, because once you outteched your neighbor, you get nothing out of it. However you can fully focus on one part of the tech tree, while constantly filling up the other side through conquest, but the 5% science penalty will hit you pretty soon. So you get a free tech, but you will get all future techs even slower. This makes the unique ability a truly double edged sword. The unique building is rather poor, because there are more than enough slots for great works of writing available in the early game due to Amphitheaters. The royal library does not offer anything else, except that additional GW slot.
Venice: Venice is incredibly situational. Well it has its great strat bias, which will ensure you the best possible starting locations before any other civilization is placed on the map. But the lack settlers is forcing you to very special tech path for optics and also going Liberty, both of which are not the best choices. And neglecting the important military techs for too long in favor of getting some early puppets could really hurt you. Not to mention, when you only get a decent or bad start or you are missing iron or coal... You can not settle there and you are doomed if no CS has it.
Indonesia The bonus resources are nice, but they are not a big deal. Any other civilization with a happiness building will easily be able to exceed that bonus. The Candi has a very situational bonus and is unilkely to give you a lot of additional faith, you are very dependent on the religious performance of your neighbors, therefore the bonus you receive from it is minimal.
Zulu: The unique unit is very strong and the army maintenance bonus is nice. However in total the Zulu are a pure warmongering civ and have nothing more to offer, unlike other civs. The Ikanda becomes obsolete after gunpowder as well as their unique unit. The moment they shine goes by pretty fast. You can better play the mongols.
