The best olive oils I've had anywhere are the local ones on Crete, which you get in bulk in the stores or in carafes on taverna tables. The best of these are off the scale. I poured some once from a carafe on a taverna table in Heraklio onto a piece of rustic bread, and it was not only the best olive oil I've ever tasted, it was one of the best things I've ever tasted.

In North America the best overall I've found, and the best value, are Turkish, but they're a little hard to find. Greek ones, more readily available, are almost as good.

Italian olive oils have a bad reputation for being adulterated or not living up to the specifications on the bottle.

Occasionally I've found imported French olive oils which are excellent but hard to find and extremely expensive.

I've never had a California olive oil that impressed me much, including the fancy expensive ones in artistic bottles.