Strangely, Northeastern Tennessee roads are pretty good. But I was amazed at how poor the roads leading into the Knoxville area were. It took about two hours to get from Gatlinburg to Knoxville. I only stayed in Upland parts of South Carolina, but those Road seemed pretty good. Frankly, Tennessee was a relief after driving I-81 in Virginia, which was two lanes when it needed to be at least three.
Trucker Mag has TN at #1.