Wouldn't it be nice if you could look at a shelf of olive oil and know which one is the best? Many people wonder who produces the best: Greece or Italy? In the contest between Greek Olive Oil vs. Italian Olive Oil there is no 'knockout', but there are points scored.
Asking to choose between Greek Olive Oil vs. Italian Olive Oil is like saying 'Canadian Apples vs. American Apples.' The winner depends on variety, care, and conditions. It is the same with Greek oils vs Italian oils. Which is better depends a great deal on the care and conditions the oil was harvested and processed under, and not so much which country did the job. It also depends to some extent on the olive varietal used, though only to those with exceptionally sensitive palates.
Italian olive oils flood the American market; most grocery stores sell primarily Italian named oils. So, if one picks a winner this way, the Greek vs Italian contest is likely to be swept by the Greeks. That's because most grocery store olive oil is ... not very good. It's usually old, and because it is mass produced its individuality is gone. The Italians have a small problem, because as a country, they consume more than they produce, which means they have to import oil just to satisfy their own demand. So where are they getting all the oil for the Italian olive oils that flood our shelves? From other countries like Spain and Greece.
Greek olive oils have a different problem, one of marketing. There are small to medium sized Greek producers who've been trying to break into the 'American Market' but find the system difficult. Because grocery stores stock items that will sell in bulk, and because suppliers pay a premium to have their groceries placed on the shelf, you are unlikely to find a great Greek olive oil in your local grocery store, if you can find one at all.
So, how can we choose a good olive oil, whether it's Greek or Italian? We have to go by taste. Greek oil that's produced and handled with care is flavorful and fresh, and Italian oil produced the same way will be just as good. After production, time is the second consideration. Even an olive oil that started out life as the best in the world will fade to a shadow of its former glory after years in a bottle. It's not wine, and doesn't improve with age. More and more gourmet stores are offering tastings, and it's a great idea to attend one. If you find an oil you like, whether Greek or Italian (or Spanish, Portuguese, French, or Tunisian) buy enough to last a year. Then do it again next year.
If you don't have access to an olive oil tasting, it might be helpful to get recommendations from those who have tasted the oils. Change your question from 'Greek vs. Italian' to 'fresh, quality vs. old, mass produced.' Both Greece and Italy produce very high quality olive oils,