regarding broad selection/variety of top cooking (restaurants) I fully agree with philforest.

Individually (in any category) you find a better one (normally at their "homeplace: italians in Italy, etc. etc. etc.

But again, as a melting pot of many ethnic-groups San Francisco has the (or one of the) best variety - and consumers which appreciate (and can afford) and a nearby world top wine-producing region (which helps a lot to improve awareness and appreciation of good food).