I was 5 years IAD based, and now am EWR based since 2012. Until recently my parents lived in Winchester, VA.
I vote EWR mostly because the airport at IAD is HORRIBLE. First there is the issue of taking the incredibly STUPID people crawlers to the terminal. Technology from 1960 still in use today because of politics.
Next there is the issue of the "trailers" tied together to form the current terminal. It's the biggest embarrassment of the free world, and we have a base there even though the government charges more in taxes on United than any other airport in America.
Lastly, EWR has, for the foreseeable future, the most diverse selection of trips and equipment which translates to the fastest movement aside from SFO where no one can afford to live with in driving distance.
There it is. One dude's opinion.