Newcastle to Edinburgh. If modern then having the class 91 alongside the IET or back in the days of the Deltic. Main preference would be North Wales coast Crewe to Holyhead in the early 80's with a class 25 and maybe a new DMU. With suspension added to the 40 and 45 (and 31).
A route i would love to drive, which sadly no longer exists is the https://www.walkhighlands.co.uk/aberdeenshire/formartine-buchan-way.shtml it would probs be a heritage route as i believe the last train to run on the was back in the 80s, the track was lifted ages ago but most of the bridges and stations still exist, either derelict or private residences now, it truly is a stunning route going through farmland, the coast and marshes and peat bogs, so far I've walked about half of it with the dog, as for stock it was a fairly heavy freight route linking a lot of fishing ports, also had a lot of small passenger stations, so a decent mix of traffic.
There's only so many routes out of Crewe so what more could they add? They went west, south and north so that just leaves... east? It does make sense to "complete the network" though if there's still demand for it. Edit: I was wrong. There's still Holyhead to the west and Shrewsbury to the SW. Those are actually requested routes and would start on the demand for Welsh content. Going through Shewsbury (a beautiful bit by train I remember from working there years ago), then down to Cardiff would connect it to another popular route and make a sort of circle.
Most wanted routes at the top: London Waterloo to Southampton Central, set in 2017 Southampton Central to Weymouth, set in 2017 London Charing Cross to Hastings, set in 2004 Any other section of ECML GEML Liv St to Ipswich set in 2019 or earlier Chiltern main line set present day North Wales Coastal set in any non-197 time period No routes out of Preston for a very long time.
I would like to see Skipton to Bradford via Keighley to include the KWVR Branchline. Also Worcester to Shrewsbury via Kidderminster to include the SVR to Bridgnorth. These would be really interesting routes and bring some more heritage lines into the game! I would also like to see the Piccadilly line, the Metropolitan Line and the Chiltern Main Line.
Worcester to Shrewsbury direct by rail hasn't been possible since 1963. I would love to see a recreation of the original SVR before Beeching but really we would need steam for that.
Marches Line from Newport to Shrewsbury would be nice. North Wales Coast remains the Grail but for us old farts needs to be set in BR Classic, early 80’s. Something scenic from Scotland with Sulzer Type 2’s or 37’s. Time to think outside the trend and get away from the double track electrified non scenic main lines.
I'd be fine with that, but only after we get 3 quality routes out of Waterloo to compensate the high amount of Preston-based routes