Do you know where you want to work? Does that employer recruit out of both schools?
At any rate, I say go to Berkley. Surely the more prestigious school. Surely more employers (or graduate schools if that is your aim) will be looking for Berkley grads.
As for the cost, education is BY FAR the single greatest investment you can make (thinking of how much it costs vs. your return over your lifetime...financial and non-financial return). The small extra investment in Berkley COULD have nice upside. At worst, you will be no worse off than the UC Davis choice. The extra cost is de minimis over a lifetime.