I think the question is provocative but meaningless (sorry chip!
For starters, China is huge, there are hundreds of different ethnicities living in what we call China, so there is no such specific thing as "Chinese" food, anymore than there is such a thing as "Earth" food
Moreover, what they serve
as "Chinese" food in Western Chinese restaurants bears little resemblance to any of the major Chinese cuisines, ie Anhui, Cantonese, Fujian, Hunan, Jiangsu, Shandong, Sichuan, and Zhejiang.
And of course lastly, even if we can pin down a representative cuisine for each country/region, how on earth can we choose just one as the best
? Although now that you mention it, from my meager experience, I would probably go with Indian and Japanese, and Thai *can* be good too.
I don't know, it would take a lifetime just to sample food from all the areas in the world to make a really educated pick anyway
<-- Yunnan Sourcing Small Bud Gold Tips. Yummy, this one has grown on me...