That's not really the right question -- it's more about the investment opportunities inside and outside the Bay Area. In SFBA, there are so many startups that if you're a median investor you are investing in perhaps the 1000th best opportunity in the area. If you are willing to invest in a place with fewer investors, you may be investing in the 1st-5th best opportunities in say, Jacksonville FL. However, that assumes that it's possible to rank order these a priori, and more importantly, that you can serve your portfolio companies as effectively when remote (you can't).

I think there are other places that can be equal. I would think that includes Boston, New York, Boulder, and maybe a few others. They key is a support network of entrepreneurs and potential employees with an interest in/experience in startups.

On the other hand, starting your business in a random town probably won't have great odds.