The best was a cousins wedding a few years ago. They had food stations that kept fresh food available all night. A cold seafood station (shrimp, oysters, crab), a sliders and fries station with the mist awesome dips, a carving station with prime rib, lamb, and pork, a salad station with fresh grilled veggies, and those are the ones I remember.
The worst was my nephews wedding last month. I have no issue with buffets, but the chicken was bland, the beef tough and the fish tasted too fishy. Then the veggies were over cooked. The potatoes were fine.