I have attended both a public and private middle school and high school and the private school was in general a much better learning environment. In some specific areas it was lagging but only because it was very small. 200 students in the four grade levels of high school.
There are good and bad teachers in both systems and I don't think you can label one better overall in providing an education. There are too many other variables.
I actually support abolishing private schools so that as a society we can all concentrate on improving the public schools. If given the chance to opt out of the public learning institutions too many people bail out and become hostile to full funding of schools.
John Thornton