Both contracts are below industry standards. Both contracts should renegotiated in the near future.

I would not base my decision on either current contract.

As the one honest, helpful thing that has been said above, go to whichever one hires you first.

The single most important factor in quality of life is living in domicile. Take a good look at the domiciles and seniority in them. I won't speak for spirit, but for frontier, we have Denver, Chicago and Orlando.