This thread derailed a bit; I didn't read every page so not sure if this was addressed:

Is OP married to Delta? The numbers for American look much better; still need to hire several hundred more this year to cover confirmed deliveries and retirements, and they have by far the biggest retirement numbers over the next few years. On their most recent bid junior captain (NY 73) went down to about 2 years. It also seems like, if you have solid quals, AA is the easiest to get hired by right now (hey, they hired me so...).

For reference I'm a more precarious position where the choice to leave for a legacy is more clear. I'm a downgraded FO at Spirit who was originally staying for the merger. I should have gone to UA a couple years ago; I'd be a 737 captain and living in base.
So yea, I also regret not leaving sooner but looking forward to anew adventure with American in the fall.