waterproof doona versus stable rug and rainsheet

A wateproof doona versus a "stable" rug and rainsheet mainy for keeping a horse dry and then warmth? Which way would you go?

Personally my horses have a lot of rugs each. They each have a polarfleece, rainsheet, med fill synthetic winter rug, summer sheets and hoods. The polarfleece and rainsheet is used in spring and autumn when the nights are cooler but days warm still, synthetic winter rug is of course for winter and summer for summer. That's just for normal wear. They also will have various sets of rugs for showing and competing as well as floating blanket. It took me a long time to save for all of them but find it much easier to have them all for each horse (so no spreading of skin diseases etc between horses) so that if the weather changes that I have adequate clothing for the ever changing seasons.