Judging by the number of wars it started in the last century... it's definitely the American.
The Chinese can and do simply disappear people without the semblance of due process. Their history also is one of ethnic cleansing as the Han people have pushed out or marginalized most other ethnic groups.
The history of: The Great Leap Forward, The Cultural Revolution, and Tianammen Square is pretty awful.
This still seems like a strange, "pre-crime" sort of standard to which to hold China. You're almost counting USA misdeeds against China: "since USA did all these horrible things, you can be sure China will do even worse, someday!"
Knowing that they treat their third-world neighbours in contempt and tend to regularly infringe on territorial sovereignty, I suspect that answer will be yes. Your media does not tend to cover such affairs.
China is one of the most exploitative world powers in its relations with resource-rich developing countries. And it's no stretch to say that without the Soviet push for communism to take root in Latin America, the USA would have had little need to support authoritarian right-wing governments there.
It's odd watching US Americans (I presume) attack China while defending their own country's horrendous record (witness your cavalier setting aside of the CIA's evil doings in South and Central America). You simply don't appear to understand that a large number of people don't like super-states and that includes both the USA and China (and also the USSR up until its dissolution).
I, as a European citizen have no practical way to benefit of that semblance of rule of law.
We are having US nukes in our backyard. This adds as much worry as it adds protection.
Our problem is often of federation. We can't just tell every state to do a thing and expect it to happen - the whole powers enumerated thing in the Constitution made sure of that. We'd have to get every district involved, replace the DAs, vote out governor's, appoint all new officials to get people who won't just uphold the status quo. Change happens from the bottom up.
We also have our own domestic and state sponsored massacres. We have mass shootings and healthcare crises and blacksites and a troubled history with eugenics and ethnic cleansing and medical and military experiments on the unassuming public.
We have labor camps for prisoners in the form of contracted call centers and menial work that pays inmates cents per hour (and "sentenced to hard labor" wasn't that long ago), and a private prison system that colludes with courts and police to keep cells full by any means, no matter the harm to it's occupants. Cash for Kids was an American Enterprise.
You might say these are lesser or more distant wrongs in the face of fresher "foreign evils", but they are no less blemishes for where or when they are perpetuated. Not fighting against them here because there's worse happening there is pretty un-American to me. Setting the example you want upheld is a pretty simple way to live.
seriously, I'm not even going to blame America. it's the tragedy of great power politics. to maintain its hegemony, it will and has done whatever takes. any illusion of moral superiority, is just illusion.
And I don't understand how you don't understand. It was a very simple point that was being made - that the US has projected far more violence outside its borders over the last century than China. It's an irrefutable point and, from the perspective of people who live neither inside China or the US and so don't have to worry for themselves about how violent those governments are inside their borders, a very pertinent one.
So it depends how you count.
Hum you could use a chat with one or more guantanamo bay inmates
There are no terrorists at Guantanamo - at least not until such time as we hold a trial to determine whether they are. In this case that's not splitting hairs, the failure to observe the Bill of Rights is quite the point.
From a pragmatic perspective, I'd choose the former.