Since I am making the same decision, I talked to students at both.
The UCLA 4th year I spoke with loved her school and her classmates. Honestly, its a great program and I really enjoyed second look there.
I spoke with a UCSF 3rd year last week and asked her tons of questions:
In a nutshell, she said her class is awesome; everyone is really smart and they are having a great time together. She said she loved the pre-clinical curriculum and it prepared her well for the boards (she seemed to have done well). She also said the clinical training is top-notch. She has a wide range of rotations all over San Francisco and is getting great training. She also said ti is very easy to contact UCSF docs/researchers to get involved in anything from shadowing to research.
So, when I was at UCLA i heard a bunch of people saying that the UCSF students are not happy blah blah...(and i later noticed that these people didnt get into UCSF, but whatever), i have found this to be totally false. the people i have talked to love the school, the city and the people in their class.
honestly, i really like both schools and in the end its a personal decision. where do you want to go to med school? where will you do better? I am waiting till 2nd look to make the final call, but it looks like i might be headed to San Fran...good luck with your decision