There are a few countries that can be labeled as the greatest, and that is usually dependent on what you label as the greatest in what area you want to focus on.
Example 1: Militarily, the United States of America (Yankee Land), is currently the greatest, because the U.S.A. is one of the best places to innovate and pay for technological upgrades to military equipment; thusly why you also see the U.S.A. as having such a large military budget (mainly for the tech upgrades that help soldiers on the field.).
Example 2: Scenery. You have multiple countries that have beautiful scenery; then you have countries with bast different types of scenery, in addition to beautiful scenery. You can label any number of these countries, as the number 1, just based off of the scenery of the land.