Where do you live? What is it you want to do for the rest of your career?

I live in a WN/UAL base so I'd stay at WN. I'm not going to commute for the next 30 years. UAL doesn't have wide bodies where I live anymore....could they add some in the future? Possibly. But for now it'd take 20-25 yrs seniority to hold CA where I live at UAL and 10-12 at WN. Obviously that'll change in the future as both companies grow and retirements go into effect.

Right now I'm parking it at WN because I see no need to chase a few bucks to fly a narrow body. Our CBA will be finalized soon enough and I'm expecting parity with UAL/DL so there's no reason for me to leave. Now if you lived in a DL base and commuted for WN you'd have to figure out whether or not you want to commute or drive to work.

Really it's a moot point unless you have offers from both.