Without even arguing DAL or AA…
Six months is huge. Go to DAL.

A LOT can happen in 6 months:
Downturn, bankruptcy, pauses in hiring due to training bottlenecks, more Boeing technical issues with deliveries or groundings, shenanigans from ENY or AAG regarding “interpretations” of the flow language, ENY divestiture, WO merger, temporary loss of medical, or a million other things.

None of those are likely, but none are impossible either. Take the bird in the hand.