Thank you for all your comments and links. Well, now that I think about it, my preferences are:

1) Window seat.
2) IFE (I travel with a laptop but I don’t want to use it during the flight and my last UA experience was somewhat disappointing, I had a window seat but no flight entertainment, no video working during my last IAD-EZE flight, I was not sleepy, so video and entertainment was more important than legroom. I wonder if AA’s IFE is as bad as UA’s (on international segments).

3) Meals (AC is much better at IFE and meals, but it becomes really expensive if you try to book a ticket thru them to other destinations).

And important but not fundamental, is legroom (btw, I’m a woman, tall but E is not an issue, of course I’d love more legroom).

Alaska as a secondary program sounds good too.

@:-)I really want miles for award tickets in the future, so that’s why I’m between AA and UA.