No, I believe AirTran seniority was more valuable than SWA seniority. Someone at the 60% mark at AirTran was about ready to upgrade. Someone at the 60% mark at SWA still has a long wait because SWA was/is a stagnant airline. I know you think that your CBA matters, but it doesn't. Contracts come and go pretty easily. Seniority doesn't.
Using that yardstick you could take any two airlines flying comparable equipment and say that seniority at the airline with the faster upgrade is more valuable regardless of the compensation or quality of the job.
If there is a start up airline with 15 737's and they are growing quickly and the upgrade time is one year then that FO's seniority is more "valuable" than a SW FO in year ten, or, prior to the SW/AT combination an AT FO in year five?
If SW had never come along and instead AT had merged with this fictional, unionized, young, up-and-coming carrier would you have argued that a year one FO at this airline had more "valuable" seniority than your seniority at AT?
I think that if you had been a 10 year FO at SW instead of a three, four or whatever year FO at AT when this happened you would be making the opposite of the arguments you are making now with just as much idealistic passion.....you would be Wave