I would choose American (note, I am NOT an american). The reason I suggest them is because their clinical trials are so long. For example pfizer's vaccine has been tested on 46 000 people with 95% success rate since June. They go through months and months of trials testing enantiomeres and potential issues with other medicine.
I am cautious about China because there is no regulation to ensure companies do not screw you over. They can produce some good things, but there is nothing to prevent someone from selling useless crap. They seriously lack regulation, everything is government owned which means there is no competition to create quality because the government decides what quality is, not the competition of the best people.