I believe a ultra-efficient modern gas furnace beats the efficiency of any wood burning appliance.
Of course an open fire is not about efficiency, any more than a vision of people sitting around gas furnaces smoking pipes and telling tall tales.
Well, lots of woodburners have an eisenglass front that makes the fire very visable and enjoyable. And, unlike most fireplaces, they actually heat the house instead of the great outdoors. ;-)
Certainly, modern gas furnaces are extremely efficient. But I'd rather pay for chain saw fuel and oil than natural gas or propane, whenever possible. :-)