I lived in Charleston for 25 years, and didn't see my favorite restaurant listed when I did a search, so here's my assessment. The place is also "all you can eat" so it also fits in with the request for those places, posted in the news forum.
The place is Bessengers Buffeteria on Hwy 17 S., just outside of downtown Charleston, S.C. The buffeteria is only open Friday thru Sunday (sometimes Thursday too), but it is great southern cooking.
There is always hash over rice, red rice, fried chicken, and barbecue. The rest of the dishes vary. There is a small salad bar with some prepared items like cole slaw, pea salad, macaroni salad, etc. There are soups, usually including catfish stew. There are good vegetables and side dishes like macaroni and cheese, hash brown casserole, broccoli casserole, and so on. Usually there is another main dish in addition to the barbecue and fried chicken, like roast beef, fried shrimp, fish, baked chicken, etc. Then rolls and cornbread, and the dessert table, which always includes banana pudding. Oh I almost forgot - sweet tea is always available.
Having been to Mrs. Wilkes in Savannah (reviewed on this site), I would say the quality of the food is similar - good southern cooking. The barbecue is very good, featuring the yellow mustard based sauce often found in S.C.
While the buffeteria is closed part of the week, the smaller sandwich shop at the same address is open every day. You can get barbecue, ribs, hash, etc., etc. One great feature is their onion rings - big puffy ones, the likes I've never seen elsewhere. Plus, there's a drive thru window. I will confess that when I lived in Charleston, I would drive thru and get a pint of hash, and unable to wait until I got home, I'd take the top off and sip some from the cup like a pork milkshake.
FYI: though the Buffeteria is the only buffet, there are other restaurants in the Charleston area and in Columbia, all owned by one Bessenger brother or another, featuring similar menues: Bessengers, Melvin's, Robert's, and Maurice's Piggy Park in Columbia. All worth visiting.