Given those three choices, Dadong--either the original 3rd Ring Road location by Tuanjiehu or the second location at Nanxincang. From recent accounts, Liqun has gone downhill (not many locals go there anymore) and is in a demolition/redevelopment zone which means access is even less appetizing than usual. Quanjude is overpriced and really nothing special, and the attitude of the serving help can be rather arrogant.

Of course, there are other good options as laid out in the post above. Different price points to meet different budgets and different atmospheric needs.