My favorite train is the local freight from the 60s and earlier. The little guy that does all the "last mile" work and has to tuck into a siding for anything else. The train that is poking around the weed grown branches or industrial areas picking up and delivering the cars to and from the customers. Back then a lot lumber yards and other small businesses got single carload deliveries. Go back to the 50s and earlier and you had a multitude of small coal yards that got one or two hoppers of coal at a time for home and small business heating. Fuel suppliers got single tank cars, or maybe half a 2 dome car even. And in those days, grain of all kinds was shipped in box cars by putting plywood gates across the door openings. Some cars even had markings painted on the inside to show how high to fill the car with each type of grain (wheat, corn, rice etc) to avoid overloading the 50 ton. These marks might have been put on by some conductors to insure the safety of their equipement with elevator loading.
All in all, a little peddler, way freight, local is to me a very fun train to model and run. It provides a lot of entertainment to switch the industries and figure out facing point and trainling point moves and how often to need a run-around. The big fast freights and units trains are exciting when they zip by, but that is it, what happens next - you wait for the next one. But the way frieight comes along and stays in town awhile and waddles around doing the business.