I vote for China.
1) Rome recieved a production boost from the last patch indirectly by the nerf on factories and other items. On a relative basis, its bonus is better and last all game.
Also, its Legions are better on a relative basis due to the decline in the LS strenght and being cheaper.
However, I think China recieved a much larger combat boost in the last patch:
1) The bug on range units doing on 4 pts of damage max was fixed; and CKN strenght was increased. Given that, CKN are simply one of the strongest units in the game for an extremely long period of time. Add in the GG superior bonus and more of them, the fact that Mech Inf when upgraded from CKN get two attacks, and the lack of the iron requirement, I think you have a better Civ for war over a longer period of time.
Three CKN and one medium strength melee unit with a GG can destroy a city in one, or a the most two attacks and be ready to rock and roll to the next one almost immediately. The Legions simply can't do that as fast. And if you don't have iron, well............