Pick a country that has a better long term economy than the US.
Pick a country that has similar geo-historical background... it's hard, US is pretty unique. Closest would be something like Australia but they have too few people.
Looks like neither of us know of any countries whose long term economics outperform the US.
I think what the user above you is trying to say is that there are many factors that go into economic performance. Tax on the wealthy is not the only factor and to say that is the reason for the economic advantage would be a bit of a stretch. Every country is very different in almost too many ways to get a real, true comparison.