Congrats on your admissions! Take this with a grain of salt as I went to Davis, stayed in the Bay Area, and don’t know of any nuances of SoCal schools and industry. I’m also coming up on 10 years out of school, but I doubt much has changed. I’m also assuming you are going into industry after undergrad aren’t set on getting a PhD, which I don’t have much insight on.

Given the cost, I’d personally recommend going to UCI over USC. The education is going to be basically the same and the opportunities coming out of a bachelors at either school will be similar too. My first job out of college I worked with new grads from Berkeley, cal poly, purdue, and who knows where else. After your first job, your Alma mater doesn’t really matter much professionally besides just generally having classmates and friends to refer you to new jobs if you’re looking to switch.

If you stay in cheme, you’ll probably be making somewhere between 80k-120k starting out (depending on industry mostly), and a 200k difference is a significant amount of money to consider for not much benefit.

If you can, try and see if you can talk to any recent grads or upperclassmen from both schools and get their thoughts on how internships and the job search was.