[dagw]

Greek olive oil is considered the best in the world

This is a pretty meaningless statement. It's like saying French wine is considered the best in the world. Perhaps true in some narrow sense, but the variations within a country are every bit as large as the variations between countries. Every country that produces olive oil produces some really top quality oil and some garbage oil

Personally I mostly buy Spanish olive oil these days. Not because Spanish olive oil is 'the best', but because the best oil I've found for the price I'm most often willing to pay at the store I normally shop at happens to be from Spain.