Arabia 18
Babylon 18
China 17 (+1)
Inca 30 (-2)
Korea 28
Maya 14
Persia 17
Siam 1
I voted for China today. China was my favorite civ in Vanilla Civ5 and I have played them more than any other civ in the game. Initially, China was okay when GG were used mostly for golden ages and the Paper Maker (UB) was good in homegrown cities because a Library is a must build and getting extra

in addition to no maintenance is great. Three changes have come about that make them tremendously better, and possibly the best warmonger in the game.
Here is why China excels at warmongering better than other civs. The UU is nothing short of awesome. Some people like the Keshik style hit and run better or the long range of the English Longbowmen. I like the CKN better than both because two shots means that they get promoted twices as fast. With G&K, they can now be upgraded to later era ranged units and are likely to have a lot of promotions already to carry over making them +1 range, 2 shot Gatling Guns and Machine Guns! Wow! G&K made GG better at being GG and not a great person to burn for a golden age. If you are unsure how to make good use of your extra GG, please have a look at my article
Placing Citadels Offensively in the Civ5 Strategy and Tips section. The article uses screenshot of Elizabeth in the Into the Renaissance scenario, but the offensive placement of Citadels can benefit any civ, especially one which gets extra GGs.
The real great thing about China is how the UB meshes with a war monger game to make puppets awesome. The reason for this is maybe not so obvious. Initially, Vanilla Civ 5 had a problem where puppets being under control of the AI would drive a player into negative

and

very quickly. To fix this, the developers patched the city management of puppets (and possibly the AI in general) to emphasize

all the time and to build a

building when the empire is in

state. Now look at a weakness that every other civ has...puppets not generating enough

. China is unique, because the Paper Maker UB is prioritized by puppets due to the

, but also has all the benefits of a Library which puppets for every other civ in the game do not prioritize. That difference can really help China to keep up in the tech race as they go on a puppet capturing warmonger spree!!!
...and it is a lot of fun!!!
I voted down the Inca because they really are the weakest civ left on the list. Despite the ease of getting both

and

in small cities, they really don't excel at anything very well. They are flexible simply because they have no direction and often lag behind when playing at higher levels.