The latter point is perhaps worth expanding on. At Oxford, you might share a room, a flat, a staircase or at least a table in Hall with someone who is studying anything from Akkadian script to Astrophysics. I found it enriching to hang out with people doing lots of different subjects.
Coming from a large state school and a large sixth form college, I enjoyed the collegiate life at Oxford, and the sense of belonging to a large organisation (the university) and a relatively small one (my college). I liked the one to one tutorials, the chance to wander from library to library, the general beauty of the environment, and the various small group interactions, academic and social.
I recall being struck by how grey and anonymous was the law school I went to in London after leaving Oxford (to obtain a Diploma in Law), and the apparent lack of variety of student life there. Go to a lecture, mooch about in the canteen, go to a class, go to the pub. Oxford had offered more variety of academic and social life, not least because it had the physical resources to do so.
Some people prefer being part of a larger group, whether defined by a university, a subject cohort, or whatever, and some people don't like the relative intimacy of life in a college.
I suspect that Oxford and Imperial are apples and oranges, but that doesn't make one obviously better than the other.