I spent most of my airline career on reserve due to the position of hitting a hiring freeze first right after hire as FO, then shortly after upgrade to Captain. It was my experience that having seniority decide every single decision caused a vast disparity in lifestyle between top seniority pilots, who had 20 days off a month, and people who were stuck 2-leg commuting to reserve to outstation bases.
It created an unhealthy competitive atmosphere where every pilot was willing to step on someone else's situation hard in order to make theirs even a tiny amount better. I applied for Netjets after hearing from friends there who seemed much better treated. From what I understood, their system was much more balanced, as most pilots were on the same 7 days on, 7 days off system, but preferential schedule only shifted the days. That would have prevented ridiculous situations like mine, where I worked every weekend and holiday.
Pilots at Netjets were also provided revenue tickets to their bases, given they lived within a certain distance from a major airport. I felt this was a much better way to treat pilots than my airline, which displaced pilots after closing a base, but forced you to fend for yourself with nonrevenue flying.
After being in the corporate non-flying world for nearly as long as I was in flying (10 years flying, 9 corporate), no system is perfect, but the industry seems to be the prime driver of quality of life, followed by company culture. If you can find both of those, even a seniority system won't put you at a disadvantage if everyone is treated well.