I’m not going to let andover20___ cherry pick the lists he presents so I’ve posted the two first links below when you google “Best Boarding Schools”.
http://www.thebestschools.org/features/best-boarding-schools-in-us/
http://www.businessinsider.com/most-elite-boarding-schools-in-the-us-2014-12?op=1
Also, @Center keep up the good work.
I think any school in the top 20 is probably the best prep school. They’re all basically identical in terms of the education you’ll recieve.