What's the best Medical school in the Us?

Top 10 based on what? Research money? Admissions? Prestige? Teaching? History?

Any MD granting institution in the USA is held to the same (very strict) standards for LCME accreditation, so they are all "good" medical schools, education-wise, USC included. Harvard is the top ranked medical school by US News and World Report most years, but they do not necessarily have the best teaching (I know a few docs who were Harvard med alums and remain firm that they have better trained colleagues from other institutions), and you will not necessarily receive the best clinical education there. On the other hand, lower ranked schools might have more emphasis on teaching than research and you will receive a wonderful hands-on clinical education, but your school will not have the same name-power or network that Harvard provides you with. So it's a little hard to say what the "10 best medical schools" are.

according to US News Best Grad schools

top 10 medical schools for primary care (not Research):
University of Washington
University of North Carolina-Chapel Hill
Oregon Health and Science University
University of California-San Fran
University of Colorado- Denver
University of Minnesota
University of Nebraska Medical Center
University of Mass. - Worchester
University of Penn.
East Carolina University

check out U.S News Best Graduate Schools, edition 2012 magazine.

USC Keck is number 36 for medical school/Research