I am fixing up some old carriages that I picked up here and ...

I am fixing up some old carriages that I picked up here and there. Some have metal wheels and some have plastic. Is there a consensus as to which is better?

Depends on what models they are. Tri-ang plastic coach wheels run lovely when clean, Hornby did some Silver Seal wagons in 1973 which had metal axles and lovely metal tyred wheels these run lovely as well, a year or so later under the Silver Seal banner they switched production to cheap plastic wheels across the range with just a metal plating in the tyre area and these are awful wheels, these wheels continiued in their range for many years. Nowadays most manufacturers use metal wheels so you could say the wheel has come full circle back to 1973 again in a way. Metal wheels are only as good as your track laying, they find every defect in the track. However metal wheels are considered to be the better choice. Bear in mind though, one wheel must be insulated, mnost wheelsets supplied have insulating bushes into which the axles fit, but check this otherwise you may have a short across both rails.

Thanks for pointing out the insulation issue. I was also leaning toward the metal.