For fit purposes, I’m a big fan of looking at a college’s version of a “What we look for” admissions page.
Everything else that comes to mind related to fit is really pretty personal.
Like, my S24 might be interested in grad school, and generally is a bit more academicky than pre-professional, although he is fine with a mix as long as the dominant vibe is not too pre-professional. He is not interested in colleges with too much of a “grind” reputation, nor the traditional big-game/Greek-life party scene. We joked at one point that a college which says it is a work-hard/play-hard sort of school is probably about the exact opposite of what he wants. He wants more of a work-smarter/play-friendly sort of college.
So we look for information on Greek life, which is available multiple places. I also like to look at per capita PhD feeder lists, including by subject where available. This gets filtered for him into some sort of general, “yes, this college has been good/very good for grad school placement,” statement. So he is not really looking at the list order in any strict sense, but if it generates some possible leads, or confirms some general reputations, that seems useful.
I note I don’t necessarily believe if a college is high on such a list then choosing it will automatically help you get into a PhD program. It is more that if a college is high on such a list then you know there are likeminded students and at least a well-established departmental effort to this end.
Along the same lines, I do look at the US News peer surveys about the quality of the undergraduate teaching (as usual they divide it up into research universities and LACs). Again, this gets filtered into a more general “good/very good reputation for teaching” sort of statement for his consumption, and it is about leads and such not any sort of strict preferences.
Here I might note I really, really wish there was a serious effort to do a broad, repeat survey of college student satisfaction with the quality of their teachers. Peer reputation surveys are better than nothing, but in my view you are asking the wrong people, and their basis for comparison is pretty dubious.
Anyway, different people would have different things like this they cared about. For us, though, outside of this stuff it is really about visits, learning about what he likes from visits, and then more visits along those lines. In fact, I think he likely barely notices even this stuff I find online, and the visits are pretty dominant for him. But there is definitely a role I am playing in suggesting visits based on what he has liked so far, including making sure it is plausibly the right sort of generally academicky vibe (loosely defined).