China for me, I don't mind because I find Asian women very attractive. Malaysians, Thai, Japanese, Indian all beautiful the Chinese mybe not so much but hey ho.
USA have been in the game a while and China also plays the long game, however much of China's growth has been internally driven, on their home market and by huge government spending through the gains on trade surpluses. The job maket is fiercely competitive to the point of surplus in professional fields. In short, unless it can establish an economically strong middle class, living standards will still be highly polarised. Added to that, their oil dependence, environmental insecurity in many regions, water management issues and unsustainable pollution etc, basically China still has much to do. ...meanwhile, the world's capital is owned by Corporate America.