While I wouldn't put Café Juanita at the cutting edge of Seattle cuisine, it definitely should be on any short list of best restaurants. But THE best one restaurant among all of the choices out there. I don't think there really is such a thing. The field is too diverse.
When I lived in NYC, I always kept up with the latest Zagats. It was a useful primer to staying on top of an overwhelming number of food choices. But Zagats has been a devalued currency among foodies for a while now. And I know a local chef who described some inconsiderate and arrogant behavior on the part of Tim Zagat which disappointed me further.
pigeonmom: I'm with you. Portland's downtown cluster of street food vendors is a model that many Seattle food truck owners wish Seattle would emulate.
They do have occasional gatherings of food trucks over in a large empty lot in the Interbay. However, it tends to get over-mobbed and people have to wait in line over an hour for food, which I'm not really into, as this isn't the 1980's and I'm not a citizen of Soviet Russia.