Good question, and difficult to answer. I have wide tastes... but if I have to name one grape wine... the first wine that made me set the glass down and marvel was a Brunello de Montalcino. And any bottle I've had of the style has performed wonderfully.
Shame they're so expensive! I sure don't get to drink them as often as I'd like.
In terms of something single varietal and locally produced, I've had some amazing Syrahs since living in WA.
Could not pick just one. Reds over Whites for sure but can appreciate them all with the right food combination. For me its the wine food combo that counts. What pairs with what. What compliments the other in such a way that you simply can't stop going back and forth to see how one improves the flavor profile of the other.......
I probably have more Cabernet Sauvignon than anything else!