Tulane would be #1 if we were talking about biological and gene research, but this thread is about the business schools--and Tulane can't quite compete with W&M and Illinois in this particular discipline.
Illinois is best for accounting, but other than that, the school's program is terribly unorganized considering their high ranking on USNW. The school is in the middle of farmland and is not even centrally located for where the town is--and Champaign is not exactly the center of the world.
W&M continues to improve almost yearly and the small class sizes really work in their favor. The school continues to attract great faculty and administrators in all departments at the school. (For example, they recently hired Sandra Day O'Connor to run their law school).
Marquette suffers from its location next to two freeways and being down by the railroad tracks in central Milwaukee. The school itself is good and its Jesuit administration follows the combination of liberal arts and technical programs you see at similar schools like Fordham, DePaul, and Loyola, meaning that the program is well-planned out--but not competitive enough to get the rankings like other business schools.
I'd pick W&M if you don't mind a small school, but Illinois if you want the athletic competitions and school spirit stuff as well.