I can't speak for mustard-based sauces, but with respect to vinegar-based, I tried Scott's and loved it. There's no sugar in it, so it has quite a vinegar & spice kick to it, but that's what I like.
Most Carolinians who prefer vinegar-based sauce use Scott's
at home. Visitors often think that there's an actual Scott's restaurant in Goldsboro where it's made, but there isn't -- not even a storefront. I always bring a bottle or two back to New England when I visit my family in the Carolinas, and it's the best sauce for cooking BBQ at home. Their motto is "The Best Ye Ever Tasted," and I agree. As for mustard-based sauce, Maurice's
in Columbia, SC is the standard that is most readily available. Carolina Treet is also good but it's not yellow mustard-based like Maurice's.