I have colleges that I’m deciding between for film and I was interested to know which one was the best for a production emphasis. The colleges I am making decisions between are, UCSC, SDSU, CSULB, and UCR. Any information would greatly help. Thank you!
Go to the one with the most recognizable acronym. 
At SDSU there is an option for a BS with emphasis in Production. However, even though you’re admitted to the school of Theatre, Television and film as a freshman, you would have to apply to be accepted into the BS with emphasis in Production after completing certain courses at SDSU. The application includes submission of a portfolio. You can see details here https://ttf.sdsu.edu/programs/program_emphases/emphasis-in-production
I am not sure how many are accepted.
CSULB is similar. They have what they call an option in narrative production. Their website says:
“Enrollment in this degree option is limited. For admission to this option, applicants must submit a portfolio that is approved by a department faculty review committee. There is no Spring admission for the Narrative Production Option.” https://www.csulb.edu/department-of-film-electronic-arts/academics/academic-programs
UC Santa Cruz has a production concentration that a student can aim to pursue. Their website said “FILM 170B students apply by submitting works created in 170B to a portfolio review conducted at the end of each quarter. These student works are reviewed by a committee of film and digital media production faculty. Instructions for the portfolio review are available at the Film and Digital Media Department office. Students should note that production courses are in high demand and that faculty/student ratios and equipment resources limit the number of applicants accepted into the production concentration. Students may reapply a second time if not accepted”
http://film.ucsc.edu/program/concentrations
I don’t know anything about UC Riverside so I can’t comment on their program.
You might want to try to contact the departments to find out how hard it is to get into their various production concentrations, i.e. what is their acceptance rate into those.