Similar anecdote: I deeply believe that Caltech is the best[0] university for me (and that's even while I'm struggling with major burnout due to an insanely rough sophomore year[1]—even though my current situation is decidedly suboptimal, I don't regret a thing).

My particular favorite aspects of Caltech are three-fold (in no specific order):

1) The Honor Code and collaborative nature, for the reasons you've mentioned :-)

2) The breadth of the Core and CS major requirements. e.g. I really doubt that I would have found a fascination for physics, without Caltech having required me to take two terms of special relativity and electrodynamics as a freshman.

3) The theoretical focus. Even though I'm a CS major, my classes are often proof-based. One (non-CS-specific) example was Ma 1a, the mandatory first-quarter freshman calculus class: It spent the first two weeks building up the real numbers (i.e. starting from the Peano axioms). Caltech's theoretical-ness has a particularly special place in my heart, because it's one of the big reasons I recently cared to learn about interactive theorem proving and formal verification (which I love so much that I'm working on a undergraduate research project in Coq).

[0] (among the universities that I know enough about)

[1] I'm honestly a bit hesitant to share about my burnout publicly (since mental health issues can have stigmas and I don't want to shoot myself in the foot re: grad schools or employers), but HN is sufficiently anonymous (at a casual glance) that this feels safe enough.