First off, congrats! Out of your two choices, I would choose EWR and live in eastern PA. I’ve lived near IAD and left the state within a few months after frustrations with traffic, local taxes, state taxes, and overall perceived incompetence of the Dulles air traffic system. I commute to EWR which is a farther and more difficult commute for me because I just can’t accept IAD issuing a ground stop to ORD because there’s a thunderstorm over southern France. The EWR crews are great, and depending on which fleet you’re on, the flying can be some of the better flying at the airline. It’s your choice though, and nothing is permanent except change.