Harvard. Bill Gates, Steve Ballmer, Mark Zuckerberg.
This not to say some schools aren't better than others, but when people do great things it's usually because of who they are rather than where they went to college.
I agree with the gist of your point, though. The school you attend is considerably more important for grad school.
But in overall you're right. Don't treat college as your pass to success, however it could be your backup, just in case if you're not that smart as you think. ;)
That being said, Harvard is probably a pretty good place to be.
To the original question: Stanford, by a very wide margin.