DD went to Cal for UG and has been surprised at the amount of respect she gets when it comes up (she’s now an MD), I cannot see the kids at UCSD being any less intelligent or driven than UCB; I imagine each is equally competitive, so go with the one that is a better fit and if it’s a toss up on fit, then add the Berkeley prestige factor. I think UCLA is also pretty similar for prestige factors.
I am all about fit over prestige, but just don’t think you are going to have an easier time at a mid-tier UC, most of those kids are equally well qualified and intelligent, they may just be missing whatever crazy hook puts the person in the Cal/UCLA accept pile.