Sorry to say it, but, for undergrad, Stanford is the place to be. Grad school is a different story.
That said, you wouldn’t be the first (or even the only in your class) to choose Cal over 'furd. 5% of cross-admits do it every year.* Some people just like Berkeley’s environment better, and, while the faculty attention and resources are wholly lesser at Berkeley at baseline, the research opportunities and caliber of peers (at the top ~ 25%, anyways) are quite similar, if not tipped in Berkeley’s favor. In fact, some thrive in the competitive atmosphere at Berkeley… I know, as an undergrad, I wouldn’t have, but some do! And the top of the top at Berkeley are highly coveted by employers & grad school adcoms.
Source: Berkeley PhD student, Colby College & Yale grad
- NOTE: source is a bit old (2006) http://www.nytimes.com/imagepages/2006/09/17/weekinreview/20060917_LEONHARDT_CHART.html