Another UC San Diego alum here. Like the others said, there are a lot of universities to choose from in California and you really have to figure out which one feels right for you. I would suggest applying to many universities based on the criteria you're looking for, then visit the ones you're accepted to so you can make a final choice. (Unless you have plenty of cash to visit many schools before even applying.) You're not going to know for sure unless you've visited them. I was accepted to three UC schools and visited them to see which one I wanted to go to. As it turned out San Diego had both the nicest campus and location AND was the one school far enough away that I wouldn't live at home. What a coincidence!
The UC system is one of, if not the, top public university in the U.S. It's gotten even more competitive since I graduated, so I hope your grades are good. The Cal State system is also very good and probably produces more teachers than anywhere else. These systems are obliged to accept the top high school graduates in California, so I'm not sure how many slots are even available for out-of-state students. Someone else might know more about this than me, but it's possible that it's even harder for you to get in. You won't see me badmouth any of the public universities here though. They're excellent schools and I'm glad the state had the foresight to establish them decades ago.
However, fees for out-of-state students in our public universities are exorbitant, basically making them as expensive as a mid-level private school. Both the Cal State system (extra $12K per year, last time I checked) and UC system (extra $16K) make it very hard to attend if you're not from California. It seems excessive, but they have an interest in limiting the number of slots that go to students that aren't from California, what with state taxpayers subsidizing their education and all. It would be surprising if you managed to establish residency within the first year, so you'd probably be spending that higher amount for the first two years of school. That's a lot of extra money to pay. Maybe you can get some scholarships to alleviate it?
Schools aside, I hope you've put a lot of thought into making such a big geographic move. It's a whole different world when you move out and all of your family and friends are hundreds of miles away. It's exciting, sure, but also trying at times. Think about why you want to make such a move. And why California instead of, say, British Columbia? Or the east coast? You have to have a specific destination in mind and not just "I need a change and don't want to live here anymore."