I don't think professor prefer Chinese student. The thing is, there are A LOT of Chinese student to choose from at any research team, so every left or right, you will see a Chinese on your team. And mostly because Chinese flooded the field in Engineering and Pure Science. (I once saw a 100 name application on a Math Program, 60 of those are Chinese name)
While I do think there are some preferential in some field, like Mathematic Principle would prefer Russian and Chinese or Historical research would prefer European or ICT would prefer indian. But whether or not Chinese student are more capable than other? I would not say it is, well, at least depends on which field you are talking about? In my field, there aren't many Chinese in my course (which is applied economic and financial field), a lot of Middle Eastern people though.