The Railway is mostly just an intelligence network, who are experiencing hard times and who have to operate under the nose of a vast surveillance system who have operatives everywhere and even the birds have cameras in them. I don't blame them for lying low. While I don't believe in their mission, I respect their dedication and level of sophistication despite their circumstances.
The East Coast Brotherhood of Steel has some potential, but I don't see them as being able to successfully govern a region or outgrow their dependence on salvaged tech tech any time soon. What's more, is that they re probably only one leadership squabble away from splintering further.
The Minutemen are good for waiting at the finish line so they can latch onto the real winner IMO.
