We have three heaters in the Winnie, the propane furnace, the big ole residential heatpump and a small coiled wire heater we bought in 2011 when the motor froze in the Bounder we had. In order of preference for me is the coiled wire heater from WalMart, the heat pump and last the propane.
The little coiled wire heater is nice because we can put it anywhere and it really is a zone heater, if it is just moderately cold, say 50 or higher, I can put it in the living area and it is nice an warm there while cooler in the bedroom.
The big ole heat pump has a higher BTU rating than the coiled wire heater and good down to at least 20 degrees, as it is a residential air conditioner it is a little noisy and ducted through the ceiling but quieter than the propane furnace which is properly ducted through the floor and heats pretty darn good.
This is all predicated on having at least an electrical hook up.
If no hook ups, of course it's got to be the propane.