Priorotize
1: Modular stations
2: Better underground bulding (the one in CIM is great.
3: More clear interface with better fault decription
For a future expansion (i rather take a full $20 expansion in front of a lot of smal DLC:s, the problem with DLC is that they mostly just provide more stuff that you can get from moding compunity anyway, but no new game funktion, that what i thing is what we really need).
1: Scenarios
2: More in game trains (can just import them from the comunity but sort away the bad stuff, would be okey to me)
3: Tweeked economic system
4:New economic gameplay, like resch and upgrades. Where you can get a like B version of a engine with diffrent gearing or more effeicent engine.