Greatest?

What are the criteria of being a great county?

Some would say military power,

If you use that measure its pretty clear who is the greatest.

For much of human history being the strongest also led to economic benefits as countries who lost were looted and their people enslaved.

This led to economic benefits for at least some of the population as the spoils of war were brought back.

Not a common practice today so a strong military is generally a resource drain.

In many ways military expenditures are a gigantic income redistribution scheme, as taxes collected are spent on salaries for military and equipment, bought domestically that creates good paying jobs building that equipment.

If however the criteria is where people are happiest or healthiest, we have to look elsewhere.

In that type of list the US doesn't make the top ten generally.  In the 2018 UN study the US came in 18th

Happiest Countries

The criteria here is perhaps something you might argue about but I don't think too many would argue that the US has the happiest people, we sort of keep shooting each other.

We still lead the world economically but that wealth is distributed more and more unevenly.

Of course chanting, we're number 18 is probably not about to catch on, so just stick with USA, USA, leave the numbers out.