not gonna lie, Air China is terrible.
Lived in beijing for a number of years and can confirm - Fly air china in business if you A) dont drink - they rarely load good/enough alcahol for a flight, was actually just on PEK-LHR, NO champagne/NO white wine/ 1/2 bottle red avail for entire flight.
2) you speak fluent chinese - crew very poor at English (not their fault)
3) Dont really care about food - the selections are poor and the chinese stuff they dish out pretty repulsive more often than not
4) you dont want a true lie-flat seat.
I would stick with BA via LHR or if goign to SFO then United via ICN or Air Canada via YVR
much, much better products. For EWR/NYC- it has to be CO