The one that comes after the signaller update that will allow to have more than 2 or 3 trains per hour
My priority would be the 7 line in New York City. This would then be followed closely by the J line in the same city. Two of my favourite lines to watch cab ride videos.
As much as I would also like an NYC subway route, why o ly be limited to just one? I think they should do PATH. It's a small system. So small they could actually make the whole system. It's longest route (Newark-World Trade Center) is only a 22 min trip one way. Service patterns varies from four routes on the weekdays to two routes weekends and overnights. It's underground and outside. It's a subway that operates under FRA rules. And with only a Fleet of PA5s, the DLC could be the older PA4s. Plus, it runs along the NEC from Kerney to Newark, which they already modeled once before in TSW2020 and hopefully will again if they remake NEC.
PATH would be cool but it's not a famous or the most recoginzed compared to the nyc subway or london underground. I think it would be cool though
I'd like to see Moscow's Metro-2 system in the game, if only for my own twistedly evil, sadistic desires of finding personal amusement in the insurmountable red tape encased headaches DTG would have to contend with through trying to gain access rights and mapping it.
The Broadway 7th ave line since the section 42nd street to 215th street West Bronx and the Lennox & White Plains road line to freeman street from 96th st broadway opened on October 27th 1904. This nycsubway.org map shows the first subway routing. In Timetable mode, pre-covid-19 Pandemic service pattern is 1 train local 24/7 2 & 3 trains Express however late nights Express to 42nd street Times Square 3 train service 2 train is local during the late nights from 241st st Bronx down to Flatbush Ave Brooklyn College. . The Brooklyn Portion of the 3 train during late nights is operated by the 4 train Extended from Crown Heights Utica ave to New Lots Ave connection to B15 bus to JFK Airport.
The Moscow metro would be very interesting. It is one of the largest underground railway networks in the world. They have wonderful stations there.