My top two favorite routes are still CSX HH and NTP. Yes, they are long, but I think what I enjoy even more about them is that they have a good selection of yards, sidings and short branch lines that are accessible and usable in service mode. In your opinion, what's more important, overall route length or variety in terms of yards, branch lines, sidings and depots?
I'd say amount of potential activity. For me, 200km route where you sit on the cruise control most of the time with a stop every 20-30 mins is far less interesting then a short route with lots speed limit changes, gradients and station stops to keep the player busy. I recently suggested a 12km route, but with 17 stops, trains every 4 mins and a mix of 'express' and 'locals' meaning the express will be chasing yellows while the local pulls in to the loop there is a lot more for the player to do in those 12km then in many longer routes.
In general, I would prefer your second alternative -- especially yards and sidings -- because I prefer switching activities; however, again in general, most TSW routes that include plenty of yards and sidings do not make adequate use of them in scenarios and sessions, so all of those potentially bustling areas default to worthless real estate. The ability to make our own activities in TSW2 excited me when I first read about it because I thought it could be used to make switching sessions that could be published, similar to the Workshop possibilities in TS, but since it will be limited to the driven train and a single destination and cannot be shared with others, what good will it be?
Yard Switching is fun. I'd love to see DTG make a new freight route with a large yard players could move cars around and recreate the operations of real yards. Some more industries served by the railroad could be included, too. I'd suggest the UP Bailey Yard in Nebraska (it's the largest yard in the world), the NS (or maybe PRR or Conrail) Conway Yard near Pittsburg, the BNSF Barstow Yard, and the UP Cheyenne Yard. Longer routes are great for faster trains (ICE, TGV, Acela, etc.). If I had the choice between yards and longer routes, I don't care either way. I love trains. I just want more heavy freight routes and later, some steam locos.
I'm not a huge fan of switching. I think routes could be longer, not in distance, but in time. Longer routes would be nice for high speed routes. GWE is pretty short if you drive the HST, but I think the length is okay while driving the 166. And I really like WSR. Even though it's a pretty short route, thanks to the lower speed it still takes a while to complete, with plenty of stops to make along the way, and pretty of scenery to admire.
To me it's not route length that's important, it's what you can do on the route. Sometimes a very interesting short route can be more fun than a boring long route.