Both for me, too, depending on the freight. I've only seen coal and aggregate loads in unit trains, so that's what I run. I also understand automobiles typically are shipped via unit train, so I run a consist of exclusively screened auto carriers from different railroads.
My favorite, though, is the old fashioned toy train consist of hopper, boxcar, reefer, tank car, flatcar and caboose in the unlikely combination of a single railroad's livery.
What, me worry?
