That varies by campus. At most campuses, CS and nursing are the most competitive majors.
CP SLO actually admits at the ‘college’ level. You can see their stats here:
http://admissions.calpoly.edu/prospective/profile.html
SJSU admits by major and publishes last year’s admission threshold here:
http://info.sjsu.edu/web-dbgen/narr/admission/rec-10079.11705.html
Interestingly at SJSU, Undeclared has a higher threshold than Marketing…
For most other CSUs, admission threshold by major isn’t as variable as these campuses. The impacted ones have a campus-wide admission threshold that would apply to business (not true of all majors).
For UCs - pulling out admission data by field of study is nearly impossible. Use this link to review freshman profiles - you are a good candidate for the campuses where your GPA/SAT/ACT are avg or better:
http://admission.universityofcalifornia.edu/counselors/freshman/profiles/
Privates are all over the map - so, research specific campuses of interest.
I don’t know your qualifications or intentions but, a word of advice; if you choose to apply to very selective schools, (CP SLO, any UC, etc) have a back-up plan in mind and keep that door open as long as you can. Perhaps your local CSU or CC.
Good luck