Answers
Ivy League - 1
Personal experience.
Oxbridge - 3
academics more enforced there
oxbridge provides better tutors and is cheaper to get in so students can relax more on classes
oxford has more academic than the other two
State School - 2
Because of the attendance level, which is higher and very smart kids that cannot attend Ivy League or Oxbridge Schols end up at great State schools because of convience and affordability.
Less pomp = lower prices for a good education (depending on the state, I'm sure)