I'll update this as I go along, and please do forgive me if some of these things do end up being suggested by other people beforehand;
A loot all key would probably have to be my BIGGEST ask. Like, honestly, crafting a bunch of stuff at once, or trying to take things out of a container without this is pretty surprising to not have! Afterall, grabbing everything from a container can save you a few of those precious seconds you'd need if someone is shooting at you, or if you need to just empty out a container to more efficiently organize your things within your base!
Ceramics, the most valuable resource there is for the regular materials barring the Uranium for the Cores.
Is very much a hard to find resource compared to the other three. the only spawners I found for example, have been in the first car for second Class and that's about it, making the resource drops from those pretty significantly important, despite how Ceramic hungry T3 gear is, its not really found elsewhere.
(yes I know there are the boxes at the bottom of the train when the resource door opens but even then, they don't really stay open for long).
I would probably suggest changing the Chemical dispensers that are in the First class cars at the statues to dispense Ceramics instead of chemicals, seeing as how most players don't really need chemicals as much once they've reached the 1st class cars, and from my observations, those massive piles of chemicals are often flat out ignored.