According to a recent survey from the World Wide Wind Energy Association, China is the world's leading producing of wind power. They boast a total of 67.8 gigawatts of wind power capacity. The U.S. is a fairly close second, with 60 gigawatts of wind power generation. Germany, Spain and India round out the top five.
Personally, I think the U.S. could probably vault to the top spot if it harnessed the abundant flow of hot air emanating from its capital.