I love Allen and Son Pit Cooked BBQ. They've got really great BBQ, obviously, in generous portions. The "regular" size sandwich is more than I can handle, but my husband always gets the large which looks to me like about 3 normal sized sandwiches put together.
What I love more than their BBQ, though, is their sides (fried okra and hushpuppies for me, please!) and desserts (these change frequently, i believe--just ask the waitress and she'll rattle off about a dozen desserts.)
They have another location, too--on 15-501, between Chapel Hill and Pittsboro--if that's closer to you. I've never been to that one, but it always seems to be crowded at lunch time!