Like life in general, the answer to your question depends on certain factors. If I was running my cars any kind of distances, I would equip them with metal wheelsets.On a smaller moodel railroads, I would use my modeling funds elsewhere. I model in HO, and have a small 10 by 12 swithing layout, where the distances are short and the speeds low, so plastic wheelsets are fine. One very unhearlded tool I use that makes a world of difference is a Micro Mark HO Truck Tuner. You insert it between the journals, give it a couple of twists back and forth and your done. It dresses the journals, and you will not believe how much better your cars will roll. It's there part number 82838 and costs about $12. By the way, I have no financial interes in Micro Mark, lol.
Tom