You've made me think about BBQ this early in the morning. I'm going to have a hard time making it to lunch.
Archibald's in Tuscaloosa is definitely worth the trip, wherever you're traveling from. Nothing else to say.
In terms of chains, I really like Jim N Nicks. I've been eating their BBQ for over 25 years, and never been disappointed with anything. Between 20 and 25 years ago when I worked in Bham, I ate a million drive through specials at their Riverchase location across from the old Loehmann's Village, and I've eaten a bunch, and ordered family and community meals to go, from their Greystone location. I will say they screwed up royally on Mothers Day by taking too many advance orders and I was late getting my food, but it was still good. Their Atlanta suburban locations are just as good, and I've eaten a number of times at their location in Concord, NC.
If you're ever in Atlanta, Fox Brothers is a must. Their "cheeseburger" is just about the best thing I've ever eaten. It's not a burger, but a sandwich with a heaping pile of chopped brisket topped with a glob of their awesome pimento cheese and slices of thick sliced bacon on top. I'm sure there are other respectable Atlanta and GA BBQ joints, but outside of Fox Bros there's not one I know well enough to recommend. Zeiglers in Acworth, GA has good chopped pork, but it's not a destination type spot.
I spend a good bit of time traveling to North Carolina, so I've hit a number of places up there. Most have the runny vinegar based classic Carolina style sauce, not my favorite, but I have to respect the region when I partake. Lexington BBQ in Lexington, NC is one of the best known names up there. It's not far off I-85 close to Business 85 and it's a can't miss if you want an exposure to that style. They're big on slaw and hushpuppies in the Carolina joints.
On the opposite side of things, I've never been a fan of Ollie's or Golden Rule.
RTR,
Tim