Build a time machine, go to your 65th birthday, see which airline is still around and/or which would have offered better seniority progression

​​​​​​Barring that, which has better base options for you and family
Barring that, who gives you a class date first.

It's a crapshoot. Both good options.

Numbers I'm hearing tossed about DL training dept for near term hiring are insane. But....I suspect that's the same everywhere.

Beat of luck