Sunday Brunch buffets tend to be major events in HK - you often need to book well ahead. They can be very good value if you like your food, and especially if you can take full advantage of the free-flow champagne or sparkling that many have.

I have recently done the Intercon one for $688 including free-flow Moet&Chandon Brut NV, and the one at Top Deck at Jumbo for $388 including free-flow Veuve du Vernay. I would say that they were both about equally good value.