UCSB is the easiest to change majors as the vast majority of majors are in L&S. UCSB has a college community, Isla Vista, where the students live.
We found UCI to be the most difficult to take classes outside of your major/department. I’m not sure if that is still true or not. UCI tends to be pretty quiet on the weekends as many people go home. There are kids who stay but it doesn’t have the weekend action that the other schools do. I’m not referring to parties but just activities in general.