I would have to recommend Ridgewood BBQ up in Bluff City, TN. About 20 minutes off of 26 @ Johnson City, TN. This is before you get to Asheville. A very unique style of BBQ. The pork is slow smoked lean hams, that are sliced thin. The sauce is sweet and tangy.
I recommend the pork platter, if there are two of you just ask for them to "split it", it's still alot of food. I'd recommend the slaw over the beans but if you are hungry get a side of beans also. And you have to try their blue cheese dip (order a small).
The slaw that comes as a side is great and has a horseradish tang to it. It is different from the slaw on the sandwiches however.
Beans are good, never sticky or gooey like some styles. I think one of their secrets is a bit of coffee in them for a dark roasted flavor.
Order a small blue cheese, it is incredible, and enough for 4 people.
http://www.roadfood.com/Restaurant/Overview/446/ridgewood-barbecue
Asheville has 12 bones which is very popular and more of a gourmet southern style than authentic que IMO.