Just to add my latest experience recently in Y on CX [I've not flown CX in Y for the last 4 years], albeit not between US and HKG, I found that the standard of service on CX in Y to have gone down dramatically (based on 2 long-haul flights)
- Cabin Attendants are rather surly and arrogant
- food quality if ok - though seem to be much smaller
- cabin attendants seem to 'dissapear' after the meal service - did not notice any offerings of water/liquid throughout the flight. Even going back to the gallery to get water/snack - attendants were quite surly (like even you going back there to get your own items, it was a burden to them)

If i had a choice between the 3 considered airlines here I would go for
1) JL - even with the stop in at NRT (if the transfer time is about 2-3 hours) - to enjoy some Japanese shopping/food
2) AA - at least service (although not the best) - but still more or less consistent and you can mentally be prepared for it
3) CX

Cheers!