This is actually hard - which is a testament to how nicely JL treats its Y customers (or how AA makes its Y customers miserable)

Seat size:

AA PE - 38" pitch, 18.5" width

JL Y (777-300ER) - 34" pitch, 19" width
JL Y (789) - 33" pitch, 19" width

Food:
JL Y > AA PE

For me, it's going to come down to:
1) if I need EQM - then AA
2) if I JL needs to be booked in JL code (zero to no RDM) - then AA
3) otherwise, JL.