I know former & recent students at all of the four listed schools–Yale, Columbia, Chicago & Northwestern–and all had great experiences & lots of small classes with brilliant, energetic classmates.
An important factor to consider when choosing among colleges & universities in the retention rate of freshmen who return for the sophomore year.
Of the four universities noted above:
Northwestern University’s retention rate was: 98%
Columbia University = 99%
Yale University = 99%
University of Chicago = 99%.