I do this route many times a year. I used to do it on CX with CX889 through YVR and connecting in HKG. The CX non-stop from JFK gets in too late to connect to SIN. So, I stopped taking CX altogther. Now I take AA JFK-NRT and connect with the JL AA-codeshare or the UA flight to SIN.

The overall flight time is less than using CX889 because you don't have the added stop in YVR. Its a shame because I really like CX but the stop in YVR and the lack of a late night SIN connection from the CX JFK-HKG n/s in HKG makes the AA through NRT scenario a no-brainer for me.