I would have to say that most people would agree that the United States of America is the most powerful country. It has the leading economy in nearly every way except for maybe GDP, but only because China has a population nearly 4 times the size of the United States, and we also have one of the largest military and probably the most advanced one in the world. We also lead the technology industry, for example, companies such as Microsoft or Apple (vs. Samsung (South Korea)?). And in terms of academics, it would SEEM that the United States leads that to, although other countries win that more (such as China in the International Mathematical Olympiad).
However, we do seem to considerably lack decent leadership within the government, and our education system is barely 14th in the world out of the top 40 industrialized countries (South Korea leads at first place). And keep in mind that even at these International education competitions, most of the top scorers are naturalized Asian-americans.