At the software companies I've worked for, I've noticed that our recruiting teams tend to focus their on-campus recruiting efforts more on the UC campuses than the CSU ones. However, they also tended to focus on schools that are nearby, so San Francisco State might be a good choice if you're considering working in the SF Bay Area whereas UC Merced might be less desirable. That being said, I know a lot of good engineers who went to UCs and CSUs and no one seems to care where you went to college after your first job.
In terms of instruction, I'd expect that the undergraduate engineering programs are similar between the two institutions. If you intend to pursue a graduate degree, I suspect that the UC system may offer better research opportunities with more prominent professors.
Wherever you go, try to build a lot of relationships with other students and even professors. Having contacts within your industry of choice can be instrumental in unlocking opportunities as your career progresses.