JL offers the most spacious economy seats out of basically all carriers. 777s are 9-abreast with 34 inches of pitch. 787s are 8-abreast with 33 inches of pitch. A350s are the standard 9-abreast but have 33-34 inches of pitch and have received good reviews.
If your priority is the comfort level of the Y seats, then JL is your best choice.