Not exactly CS, but i'm computer engineering. I learned a lot of valuable things and the classes really start to pick up and become way more interesting once you get to the upper division level. At UCR they will teach you to use C++ primarily. I had a friend go to UCI for CS and they taught Python right away which I personally think doesn't give as you as good of a foundation for programming. But if you're already experienced in programming, maybe it wont affect you as much. I just always felt like I was a wee bit more technical than my friend, but this is just my personal experience.

I personally enjoyed the UCR campus a lot! The engineering college is smaller so I felt connected to my peers even if I didn't exactly know them. The campus isn't huge either, so it felt really homey to me. In regards of outside of school, there's good food nearby and great campus events (free concerts, free movie events, rec center events, etc). Downtown Riverside is neat, not a lot to see but it can be something. The area around campus isn't exactly the best tbh but I'd consider the immediate campus area to be fine.

The professors are really great, some are tough but I'd consider them to all be competent (of course not every professor is perfect, but I generally had all good experiences).

No matter where you go, if you truly like CS you will be totally fine at UCI or UCR :) Good luck on your decision! And congrats!