>Both programs are very good, the specific PI is going to be much much more important than any generic advice you glean from this thread.
I completely agree with this- your advisor will be the most influential factor of your phd years, for better or worse.
Also, some programs have a reputation of enrolling a lot more students than there is actually room for, with purposeful high attrition during the first couple of years. I am not sure if Stanford or Cal have this reputation or not, but might be something to look into.