Hello, ok here is my opinion.
Do not decide on a school based upon reputation. If you go to UCLA, Berkeley, or UCRiverside, you will be in a great situation, all of the UC's are great. Sure UCLA and Berkeley have the highest reputation, with UCLA starting to slowly beat out Berkeley especially in the life sciences.
All the schools you are considering will give you an equal education. There will be absolutely no difference in content when you take classes like o-chem, bio, physics, etc.
However, do not chose a school based upon name. Consider location, student body (racial make-up etc), neighborhood, etc etc.
I go to UCLA, and I must admit it is not what I thought it would be. I'm a junior, and even my junior classes are large lecture halls. A typical class is 200 students. Having one-on-one time with the professor is difficult, because there are always like 15 students waiting during office hours. You are lucky if you get a question in.
UCLA depends mainly on graduate students to hold discussion sections. These sections are usually an hour long, and a graduate student goes over the lecture one more time and answers questions. I would have to say i've had only 1 TA who knew what he was talking about, the rest actually have given me false info from time to time. Remember these are students who are also taking classes, they have homework, they have to study, and they have tests to take, they are not teacher replacements. Sadly, UCLA uses them as teacher replacements.
I've heard from friends at Berkeley that Berkeley isn't any better.
PS.... I've heard that irvine is really tuff and competitive also.
Most of my friends with wonderfull college experiences are going to small private colleges. So look into these type of schools, and many offer full financial aid to students who cannot afford the tuition.
NO matter where you go, it is ultimately on your shoulders to do well. I get A's at UCLA, but I put in lots of time.
Just remember, no matter how low you feel, or confused, you will turn out ok. Education is a small, important, but small part of ones life. In 10-15-20 yrs, it won't matter if you went to ucla or riverside, or a state school for that matter. In 20 yrs you will have a family, a good job, and everything in your college years like should i go to ucla or riverside will appear silly when you look back.
Take care and good luck, you will do great!