If its store-bought, we prefer Stubbs and Sweet Baby Ray's. The other store-bought sauce my wife prefers is Sticky Fingers Carolina Classic, a mustard based sauce. That KC Masterpiece seems to have too much liquid smoke in it. (heck, I can add that myself if I really want it.)
Howsomever...having said that, we have found that our all-time favorite sauce is HUBBA BUBBA SAUCE (a home-made). Dee introduced it to us at the first Gathering in Augusta, sent us the recipe, and we love it. We can adjust the heat by using less cayenne pepper. We use a little less than 1/8 tsp. It takes only a few minutes to make...I keep most of the ingredients together in a special box so I can bring 'em all out together and mix it up.
Deb would not use anything other than the Sticky Fingers until I quietly and timidly asked her to try this one. Now, she thinks I know what I'm talking about when it comes to BBQ sauce.