Many very delicious wines from Corton, as listed by Claude and others, but few indeed that are a clear grand cru expression. It is not the fault of the terroir or producer but of classification.
Which has sadly put people off the appellation - though with the benefit that prices from most producers, especially those based on the hill itself, have remained very reasonable. I have very much enjoyed wines from Vincent Rapet and Christine Dubreuil-Fontaine in addition to names already cited.
To answer Brian, I think that a genuine grand cru needs a depth of fruit, a range of flavour and a personality of its own over-and-above the character of its village to merit the top classification.
Clos du Roi would come closest - I can hear a rating of Fine Plus emanating from the lips of Clive Coates.