The United States leads the world as the strongest economy, with a GDP exceeding $27 trillion. Its success is due to its technological innovation, robust financial market, and ability to attract global investment. China ranks second, with a GDP close to $20 trillion, standing out for its investment in infrastructure and digitalization.
The best economy or the biggest economy? Some small countries have great economies, but their small population leads to a small GDP.
The best economy according to what criteria? Nominal GDP per capita? Ease of going business? Equality? Industrial capacity? Innovations and high tech sector? In my opinion the "best economies" around the world are Taiwan, Singapore, Hong Kong, Switzerland, Israel and the Scandinavian countries. I think that many economists consider Taiwan and Hong Kong to be a part of China, which boosts the overall results for China.
I also dont get what is "best economy" as there are so many criteria's to evaluate and rank countries. It even makes harder to find that "country with best economy" when every country has debts and given credits. OP has mentioned US to be the best because they have largest GDP, but they lead list of countries by debt with more than $25 trilllion debt.