Blackpool Branches for me, but you'll need the various layers as well to really add to the experience
One moment I dress up as a magician and try to read your mind. If it were me I would take either the Salzburg-Rosenheim or the new Frankfurt-Fulda (or the Bremen-Oldenburg). The problem is that I prefer modern German rolling stock. What do you like to drive: diesel, electric, modern, old, English, German, other?
Personally, in no particular order of preference: Southeastern High Speed Brighton Mainline (if on PC with timetable mod and Class 700) Suffragette Line
It really depends what you want. Provided you don’t mind 99.9% undiluted Electrostars then BML takes some beating. If you want sustained fast running then ECML Peterborough to Doncaster. For classic traction I would say a tie between Blackpool and NTP. For the US, going out on a limb here and would suggest San Francisco Corridor with the Baby Bullet and MP15 still the best all round passenger route. For Germany, Dresden to Riesa still takes the top spot.
Brighton Main Line, Southeastern Highspeed, Blackpool Branches stand out as the best TSW has to offer. Brighton Main Line is made better on PC via the use of mods which enable Thameslink services. Southeastern Highspeed and Blackpool Branches made better with all layers enabled.
Ok seeing as I picked one and everyone else is cheating haha. 1, Blackpool branches 2, West Somerset Railway 3, London Commuter.
1. LIRR2 ( 4th biggest passenger timetable in the game with the most branches out of any route in the game). 2. BML ( biggest timetable in the game a no brainer. my top choice for tod4) 3. Frankfurt (just love the variety and this route just has everything you want in a route. just a great route)
These routes are all TOD4, have decent scenery, and good replayability: DE: Nahverkehr Dresden - Riesa UK: Blackpool Branches US: LIRR 2