I mean this is a tough question, I don't know if there exists objective data on that. From pure logic, for Tsw2 it should be the three main routes since everyone who owns Tsw2 has access to them. For TSW I think at least a good guess are GWE and MSB but honestly I couldn't tell you. There will be many people here who have different favorite routes and claim theirs to be more popular than others probably.
Maybe DTG know the stats. There will be two measures of what’s popular. Sales numbers for DLC but more importantly how much people use each route they have.
Can you make it so that we can vote for at least two- I have three favorite routes (BKL, SKA, and GWE (GWR))
Ok Righteo. Also, someone should think of a way to say what routes they want to show where they live or something (Metra for me- I live outside of Chicago and I love passenger services)