I like very few commercially available or famous/not-so-famous
restaurants sauces. That being said after finding a location of Mike
Mills' 17th Street BBQ right off I-57 in IL, both his regular and
spicy sauce are nowpart of my pantry. I tend to be a sauce minimalist
- let the wood do the work - kind of cook and so almost always go SOS
(sauce on the side). Also after searching for a good "white" sauce
for chicken I found only one worth using - JD's regular and spicy.
Not many white sauces are available even in the South and don't bother
with Bob Gibson's.

And if you doubt the importance of sauce watch some BBQ contest
coverage or BBQ Pit Masters on TV