My 2 cents
Having recently done on AY J JFK-HEL & HEL-HKG, CX J HKG-NRT & NRT-HKG & HKG-LAX(all on a spiffy USAir 90K redemption!) and AA F JFK-LAX & ORD-LHR in J I can say there is typically superior service on both CX and AY. Not to be dismissive of the 1-1 seats on the A321T(or the FA-PAX ratio of 1-1) FAs, F&B, etc. receives just a little more attention on "foreign carriers."
Running short of time so that is only my 1 cent...