Regarding a recent class, some of the reasons for coming to PSA were listed as (not in any order) Pilot base locations, the increased pay, flow, QOL reputation, friends/acquaintances work there and recommended it, quick upgrades to left seat, commutability, SAP, etc. So no particular thing but when compared with other airlines, they felt PSA had the best package for their needs/wants. And of course, most had other options.