Hello,
My mother and MIL are travelling from Delhi to Los Angeles for 3 months and I am looking options for them. They are not in best of health, so I am tying to select airlines carefully. I will be booking it in Economy class, with meet and greet (or wheelchair) for both of them because they are first time travellers. Here are my options of flight and their travel duration/halt

By Etihad :-
Jet (737)+Etihad (777) Duration 3.50 - 1.55 - 16.45
Etihad (777)+Jet (737) Duration 16.20 - 2.05 - 3.35

By Emirates :-
777-300 + A380-800 Duration 3.25 - 2.45 - 16.00
A380-800 + 777-300 Duration 15.50 - 2.25 - 3.15

By Qatar :-
787-8 + 777-200LR Duration 3.45 - 3.20 - 16.00
777-200LR + 787-8 Duration 15.55 - 1.55 - 3.35

By Cathy Pacific :-
A330-300 + 777-300ER Duration 5.40 - 2.35 - 13.15
777-300ER + A330-300 Duration 15.00 - 1.15 - 6.10

Nearly all are taking close by time, except Cathy is little longer. Is there something, I should consider while comparing ? Like transit during halt or seat comfort (depend on flight model I mentioned) or anything else ?
Is it better to cover short duration first and then brutal longer in second stretch (like Qatar/Emirates/Etihad) or Cathy should be less killing (5.40 + 13.15 hrs) ?