I also agree with what has been listed above. Known passengers, great destinations, QoL, Family Atmosphere, in the loop on Flight Planning, Expense Account, Lots of time off (at home), good pay, excellent benefits, great equipment (very well maintained, modern, all glass), advancement on merit/hardwork, safety oriented, etc...
I have all the quals to go to any major (if they were hiring), 8,000 hours, 5,000+ jet time, several thousand of PIC Jet time, 4 year degree, yada, yada, yada... Never had any interest in the airlines... But that is just me...
When I was in college and the hope of being a Military Pilot fell through, my girlfriend (who is now my wife of 11 years) asked me if I was going to go work for the airlines instead, I told her "No, I'm gonna be a Corporate Pilot, the airlines don't appeal to me..." shes asked what a Corporate Pilot was... My answer was "I'm not 100% sure, but I'll let you know when I get there!" That was a couple weeks after I soloed... I had about 20 hours Total Time...