Does Santa Cruz use a letter grading system yet? If not, then UCSB would be the better choice.
I haven't followed UCSC in years...so I have no idea if they still use no grades...all pass/no pass. Or if they finally adopted a regular grading system...A-F. If they have changed to actual grades...then sure, go for Santa Cruz if you like it better. It's a great school in a great location. Doing well at either school will likely get you into med school....as long as you have the rest of the package (EC's, MCAT, etc).