It is difficult to determine the "best" school in the University of California system as it depends on individual preferences and needs, but some of the most highly ranked schools in the system include UC Berkeley, UCLA and UC San Diego.
UC Berkeley is consistently ranked as one of the top public universities in the United States and has a reputation for its strong programs in engineering, business, and environmental studies. Berkeley is also known for its research excellence, particularly in fields such as physics, chemistry, and biology. Berkeley is considered as one of the top-ranked public universities in the US, and it is often compared to other highly-ranked universities such as MIT and Stanford.
UC Los Angeles (UCLA) is also consistently ranked highly and is known for its strong programs in business, law, and medicine. UCLA also has a strong research reputation and is considered one of the top-ranked public universities in the US.
UC San Diego is also considered one of the top-ranked public universities in the US, known for its strong programs in science and engineering. It is also considered as a top-ranked university in the fields of Computer Science, Economics, Biology, and more.
It's worth noting that the ranking of universities depends on the ranking system and the criteria used, but generally all UC campuses are known for their quality education and research opportunities. When comparing to other universities, UC system is considered to be among the top-ranked public universities in the United States, and it is often compared to other Ivy League universities such as Harvard, Yale, Princeton and more.