On the 0 stuff, analog. The 3-rail has a memory-type walkaround (tethered), start running, unplug, keeps doing what it was doing while you walk to the next box and plug back in.
In another scale/gauge, I have been using exclusively radio control, battery power for 20 years. The earliest radios still function in the locomotives they were installed in just fine. I have moved almost 100% to NiMH batteries from NiCads.
I get 3-9 hours on a charge, depending on MAH rating of the batteries and the load on same.
I have sound now in, oh, over half of them. Had to do it for business reasons (to show how it works), but I prefer to run the volume all the way down when I run. You can hear if the locomotive has any issues that way, tighten what needs to be tightened, oil what's dry, before it fails.
Sam