Well, the great thing is that you can’t really make a bad decision here. OP, I’m a Cal grad who has a lot of relatives at both Berkeley, UCLA and otehr UCs. I really honestly believe your daughter would like either place.
But if your – and her – gut says, I just LIKE UCLA more – than pick UCLA and don’t turn back. Don’t pay attention to the “Berkeley is perceived as academically stronger” thoughts… fact is UCLA is a world-class school and so is Cal, they may have their own strengths and weaknesses but academically the difference between the two is small and growing smaller by the year. I don’t believe that UCLA students are less stressed – they just seem like it because they’re in shorts and T-shirts for much of the year. And some people prefer the quarter system because it gives them access to more courses (and if you have a class you dislike it’s over sooner.) It really is a personal preference, but students adjust to either
Advise your daughter to go with her heart, and then dive into either school’s incredibly rich, rewarding, frustrating, challenging, and ultimately life-enhancing culture.