Williams has the most highly ranked in terms of academic reputation and the amount of scholarly work that is published in leading journals. They have most the cited teaching faculty of any of schools you asked about. Job placement/internships (management consulting, hedge funds and i-banking) and track record of entrance to top econ grad school programs is also noteworthy. You should compare the econ department websites of the schools you asked about. Williams econ website has an impressive line up of teaching faculty and course offerings. The econ department is much larger than those of the other schools. If you have a math/quant background, Williams also has a very well known Math department which compliments its econ major as well.