Its Pork and eveyone has their own "special recipe or rub" for how they cook/smoke it. I've tried it all around my area within probably a 200 mile radius and we have a place in Greenville that we frequent often and deem as the best available.
In fact, I had BBQ there at "Charlies" last Tuesday.
The "best" was Ron's Hog Pen BBQ here in Boiling Springs, but Ron had health problems and retired and closed it down. We have other places but its just not as good. The "pulled pork" here is awesome. Pure "hog heaven" pun intended.
I lean toward the ketsup base sauce a little more than the mustard base depending on the recipe.
With all respects to the Kansas BBQ I remember the first year Victoria and I went to the Reunion (2008) and we ate at "Stacks". She still laughs at me because I told her "I didn't order Roast Beef". To me its roast beef with some BBQ sauce poured on it. Nevertheless, I'm a sport about it and have eaten BBQ the past 5 years in Kansas!!!