CalTech is the tops in my book on this. I don't have a huge sample size, but they are all rock stars. I've met a few less than impressive MITers.

What surprises me is that the Ivies can still have such high average test scores and GPAs despite all the legacies and athletes.

What surprised me about Princeton was that it was Lacrosse. Lacrosse. It convinced me that I want to send my kids to fencing lessons after their math circles.