admittedly im biased based on my own personal experience but even at a general level it is hard to argue that the best startups have not come from the valley and the best people naturally want to be where the best startups are.
You really haven't given a reason at all... only ad hominem. "Best people naturally want to be where teh best startups are".
I think the best startups are in Seattle, and I've compared both regions. I'm not saying people should move to seattle, though, because "Best" is a fuzzy quantity.