Interestingly enough, due to Delta hiring a lot since 2014, a younger pilot will have better end-of-career seniority at DL vs. UA, assuming equally sized seniority lists. This is because DL will have more retirements in the last 10 years of their career than United, potentially because the average age of those hired 2014-COVID trended a lot higher than the younger average age of new hires post-covid.

United still has around a 6% advantage over Delta during the majority of the career at this time with 16-17k pilot groups.