For store bought sauce, I would say Texas-Texas good to the bone, is probably the best, but I am sure it is regional. Not overly sweet, and full of savory flavor.
The next best sauce would be "Stubbs" which can be found everywhere, and comes in many styles. Original or Mild is what I use most for groups, but they also have spicy and sweet heat as well.
Next on the list is Head Country with a similar profile, available in some Sam's Clubs stores.
If you like sweet, the the suggestion of Sweet Baby Rays is good, as well as Dinosaur BBQ Sauce, and Garland Secret Six.
There are so many choices, try some of them and find a favorite.