I love a good buffet (and sometimes a mediocre one!), and will usually do one on a Vegas trip, but lunch or dinner for me. I do realize the value is nowhere near what it was 20+ years ago (I remember $1.99/$2.99/$3.99 for B/L/D at Tropicana probably 30-35 years ago.) but I like the variety.
My favorite in Vegas has been the Bally's Sterling Brunch, but haven't been to it in a handful of years. We did the Wynn Jazz brunch which is a hybrid buffet (you can order mains a the menu but they had seafood, carving stations, waffle bar, desserts and some other stuff buffet-style) 2 years ago which was great.