There are several university ranking systems that are widely recognized and respected, including the Times Higher Education World University Rankings, QS World University Rankings, and U.S. News & World Report Best Global Universities Rankings. Here are some of the top universities in the country according to each ranking:

Times Higher Education World University Rankings:

1. California Institute of Technology (Caltech)

2. Stanford University

3. Harvard University

4. Massachusetts Institute of Technology (MIT)

5. Princeton University

QS World University Rankings:

1. Massachusetts Institute of Technology (MIT)

2. Stanford University

3. Harvard University

4. California Institute of Technology (Caltech)

5. University of Chicago

U.S. News & World Report Best Global Universities Rankings:

1. Harvard University

2. Massachusetts Institute of Technology (MIT)

3. Stanford University

4. University of California--Berkeley

5. California Institute of Technology (Caltech)

It's important to note that rankings can vary depending on the methodology used, and that choosing a university should not solely be based on rankings. It's also important to consider factors such as location, programs of study, extracurricular activities, and overall fit.