Laurel is the Maryland equivalent of Herndon and equally difficult to get to. Neither are great options for those w/o a car.
The Grand Central crowd was always better than Laughing Man's. Smaller group, more knowledgable fans. They actually will hook up a computer and stream preseason games.
Can't speak to the Exile's gameday scene as I didn't find out it was a Bills bar until after the season. Solid beer selection, though, as I've been there a few times for drinks.
Again, I preferred Duffy's b/c a) awesome wings, b) extremely low key, and c) I could run home at halftime and smoke a bowl.