Despite the obvious exceptions, Asian guys are definitely smaller.
As Chinese myself I never used to like Asian guys - but not because of their small cocks. I found them mean, possessive and manipulative - with huge chips on their shoulder toward black and Caucasian guys - probably because of cock anxiety.
Things seem to be changing for the better, in Australia. And even though I am still a size queen, a juicy,pretty and charming Asian guy now does it for me more than any time in my life.
I grew up in a satellite town of a major city in which my family was the only Asian family in the city!! I was the pretty little oriental eye-candy for the entire town. I never met an Asian boy other than my brother until university.