It's a valid point to think autocracy is better than corruption.
I disagree on the level of corruption in the US I think, as far as I understood you. I do not deny there is corruption though.
I would be interested in knowing the level of corruption in China but I think the autocratic grip on the press is too strong to have any valuable data.
First, I'm not convinced that US is less autocratic than China. European countries of course are, but US is not a functioning democracy anymore; it's corporations who decides how the Congress will vote, not citizens.
Second - I think we might be using a different definition of "corruption". In US many mechanisms that would normally be considered corruption are legal, and thus aren't technically a corruption.
And yeah, would be great to have more reliable numbers for China. I don't think that's due to the "grip"; rather, it's a cultural thing: Chinese don't seem to value openness same way we do. At the same time, China is absurdly huge; I'm not sure we can have reliable numbers for all of the geographical Europe, and China is twice that.