Both are wonderful colleges!
Colgate: some required courses that everyone takes that provide a common experience
Hamilton: one of the nation’s few colleges with a completely open curriculum (along with Amherst, Brown, Grinnell, and Smith, according to Hamilton’s own brochures)
Colgate: division one sports
Hamilton: division three sports (NESCAC)
Colgate: heavy fraternity/sorority culture, with residences, although a new housing system aims to build social alternatives
Hamilton: there are frats/sors, but these are nonresidential and required to welcome all to their parties
Colgate: uniformly beautiful, unified look to buildings
Hamilton: two sides to campus- the light side that looks a lot like Colgate, and the dark side that is modern (formerly the campus for Kirkland, a women’s college, that merged with Hamilton many years ago)
Colgate: compact campus
Hamilton: large campus, with two parts (light and dark), and a root glen/ hiking trails
Both: loyal active alumni- and Colgate has a funny tradition of alumni wearing Colgate gear on the 13th or something like that
Both: excellent academics
Hamilton is famous for its emphasis on teaching students to write well.
Purely subjective view of one family:
Colgate: a surprising number of students were so good-looking that it looked like they should be models
Hamilton: interesting mix of many types of students, all interacting, although the students will tell you that there are playful stereotypes of the light siders (athletes and preppy types) and the dark siders (artsy or hipster or granola types).
Socially, Hamilton felt to me like Bates, Williams, Middlebury, Bowdoin, Amherst.
Socially, Colgate felt to me like Lafayette and Franklin and Marshall. We did not visit Bucknell, but I would think that it would join this list. (Son liked Colgate more than Lafayette or Franklin and Marshall.)
We liked both colleges a lot, but Hamilton was one of my son’s top choices and one of the final five considered for ED. It was one of the friendliest, warmest colleges we visited. Everyone was SO nice!
Colgate people were very nice, too- in fact, at Colgate, a pretty girl we asked randomly where a certain building was walked with us across campus to show us.
But something about Hamilton just felt really, really positive and friendly.
And we liked the light side-dark side stuff: it felt like there was a wide variety of people and there would be a diversity of views and activities.
I definitely felt Hamilton was a very comfortable social fit for my kid. He would have found his people at Colgate too, but Hamilton felt like a slightly more perfect fit. From your descriptions of your son, at other times, I might predict Hamilton would be a slightly better match for him as well. If he returns to Hamilton for an interview (if he did not interview yet), Colgate is really close, so he can check it out.
But really, you can’t go wrong with either of these two stellar small liberal arts colleges!