I recommend the weekend brunch at Morihachi Yakiniku. I am a huge fan of this buffet. Quality is decent and has freeflow of drinks too. Normal price is over $300HKD, but Groupon brings it down just under $200HKD. Note - this does not include a service charge.
http://www.groupon.hk/deals/hong-kon...ffet/721260395 Also, note valid locations from the Groupon - it's not all the locations.