Like everyone else, a tough thing to define. Some of my highlights would have to be:
Rocholi Pinot Noir-tasted ten years ago or more, so I cannot remember the vintage or vineyard designate. Still, the first "premium wine" I'd ever had-delicious, peppery, structured Russian River Pinot Noir.
Some more recent and less famous ones that really, really blew me away and would have to rank up there.:
1999 Cafaro Reserve Caberne Sauvignon-what an awesome, balanced earthy Napa Cab. Delicious.
2000 Niebaum Coppola "Rubicon" Meritage Delicious, earthy red blend that was almost worth the price
Podere Il Palazziono Grosso Sanese Chianti Classico Riserva. Amazing dark, earthy, complex chianti. Delicious even if not considered typical.