bencgilmore said:
Leon Litwack was incredible (RIP).
I never understood the love for Prof. Litwack. I took his history 10B in Wheeler auditorium. He read his lecture off well prepared notes, which was fine. But he didn't really show any passion about his topic until we got to early 20th century and the IWW section. Also, he was aloof with students.
For my, I much preferred Prof. James Kettner (R.I.P.). He was soft spoken and lectured in small classrooms, but he always left time for comments and questions. Additionally, he was always available to students (and former students) during office hours and often outside them. Even though he was a graduate faculty advisor (including vice chair of the history graduate program), he always welcomed undergrads and advised us, too.
I wound up majoring in history, in no small part, due to Professor Kettner. I just kept taking classes he taught because I enjoyed his teaching style so much. When I graduated, I made sure to take some pictures with him, too.
Bringing this back to OP's question, my advice would be to ignore the "big names" who lecture in large rooms. Find the professors who care about their students and passing on their knowledge. Cal's a huge university; there are plenty of these professors around; just look for them.