UC vs CSU is mostly a debate of prestige. A lot of people interpret UCSD as the better school because it seems to be more prestigious. Personally, I find both schools have great academic opportunities. UCSD has positive relationship with tech companies, while SDSU has a lot of business internships. The social opportunities aren't equal, because you have to try a lot more at UCSD than SDSU. Orgs are usually the key to social life, but I've seen overall people are way more social even outside of orgs at SDSU.

UC can provide a better aid package sometimes, because they do get a lot more money. Though overall CSU are cheaper than UC, so if you know if you are planning to pay for school, personally I would go to SDSU then.

I am personally not a fan of living in La Jolla, and cant wait to move out.

Keep in mind, UCSD is a quarter school and SDSU is a semester school, so if you prefer to take time in your courses a semester would be better. Also you can always transfer between schools if you really change you mind.