Delta guy here. Delta has been great and will be great for you too, but in your situation I think I would choose American. Sure Delta is better ran (for now), has less debt, and is a nice place to work. However, I think your seniority will be a lot better at AA and being able to live in base, if you can, increases QOL exponentially. There's always the chance that AA closes CLT eventually, but you run that risk anywhere. Both airlines will change drastically throughout your career, but seniority is constant and is a huge part of airline life (and being able to live in base while your kids are young will be great).