I just sent some friends DL JFK-TLV and CO TLV-EWR. they were in Y and as much as they enjoyed having an empty middle seat on DL going over. Once they got back and flew CO in Y they told me as long as DL is flying the 763 or any plane w/o AVOD they prefer CO

I kinda of understand as in the past month Ive flown UA on 6 long haul flights (Intl) and miss COs AVOD which always kept me occupied

For C CO doesnt have any lie-flat seats as of yet and DL might on some plkanes but not all. So if the in-flight entertainment isnt important to you then Id go with which ever offers you better timing of their flights as wella s which works better for you JFK or EWR.

If going after 6/30 a drive down to PHL and catching US in Envoy would probably be the best way, Y is only 30" so Id skip that but would most definitely do the drive if I was going in C