Should I go to a low-ranked school where I can shine, or an elite school?

Actually, UCSD has excellent science professors and research facilities, excellent students, and it doesn’t translate into their students getting into med school at above average levels to the point they’re investigating as to why.
Pomona, due to their undergraduate focus and low faculty student ratio would have the best premed advising and they don’t deliberately weed out.
UCR regents and USC would be two other excellent options.
UC Berkeley is another great Orion if you’re not committed to premed.