Current F9, former PSA. I enjoyed my time there and it was fine. IMO the most flexible regional, you can have a very good QOL there. I would still choose F9, if you have the option.
Its only a little over a 2 hour drive from DCA-PHL, so depending where you live in the area you could theoretically bid reserve out of PHL and sit at home, or enjoy a cushy line with decent block hours out of PHL if you plan to build time and leave. If you’re only there in DC for 4-5 years you may just find you like F9 and no longer want to leave if you have the opportunity to live in base. I definitely recommend the drive and not bothering with flying commuting. Retirement at F9 is very good, easier flying, nicer airplane, and better destinations.
With that said, if they both offer you a job and there’s a several month advantage to going to PSA then I would go there and not have regrets. You can get somewhere else soon enough and hopefully have a good time there while you gain experience. Good luck