I totally vote for the Chinese. Great UU (the Riders are not only effective but also well timed for Golden Ages), and as a military civ, you get cheap barracks and (perhaps more important IMO!) cheap harbors! Most important of all (for me) is INDUSTRIOUS. LOVE those fast workers!! Finally, you take out of play (by being them) an opponent that is dangerous. (I like to often play random enemies. Hate it when I get Aztec, Zulu, German, Babylonian, Persian, and Chinese as my opponents, as I once did ... that game was TOUGH! At least the French weren't too bad as the last ones!)
OTOH, I dislike having Mao as my leader, and tend to change the civ name to Siam, the leader title to "The Mighty " and leader name to "Aiko" ... my siamese cats name! But I leave all the other civ characterics the same. I do use other archrtechtural styles when controlling the building of my leaders Palace.
, I'd have to say that the Persians are the best civ in the game. The industrious trait is the strongest in the game when properly managed, scientific is not great but it does give bronze working to start, which leaves Persia only one tech away from iron working and the best UU in the game, the Immortal. An immortal rush is so devastatingly powerful that CivFanatics stopped allowing those tiny map Deity victories in their Hall of Fame. The industrious and scientific traits allow Persia to either warmonger or peacefully develop with ease. The slowness of the Immortal is compensated for by the fast speed of roads built by Industrious workers. I am convinced that Persia is the best civ, which is why I never play as them (it would be too easy). 
