Originally Posted by Infinite1K

Personally I’d stick with the AA F flagship service.

At JFK, you’ll get access to Chelsea and SoHo lounges. Even though the C123 UC at EWR is one of the better United Clubs, it is way of the mark compared to what you’ll have access to at JFK.

Seatwise, with the 1-1 configuration you’ll have direct aisle access on the A321T (or depending on when you are flying perhaps you’ll get one of the 772 or 778 they are going to be running on the JFK-LAX route). With United, you’ll be in the 1-2-1 configuration and if you don’t get an odd numbered row, the seat won’t be as nice as on AA.

Service wise, United’s F&B won’t be as good as AA.

And in the case of IRROPs, only very few flights are operated with true Polaris seats. The rest will be a mix of old 752 in the 2-2 configuration or the 777 HD with the dorm room 2-4-2 configuration. So if you need to switch to a different flight, you’ll loose the seat experience. With AA, they run a more consistent fleet so you won’t have that issue.