I've only really visited three since I kinda didn't travel to visit that many colleges before choosing one(and the one I chose I never even went to).
But, I must say Columbia is very beautiful just from my short visit...
My own college, the University of Rochester looks like a ghetto version of it in many aspects, lol, but in the springtime it has it's own charm(during the winter it's too cold to care)
I've also visited Harvard in the past and part of MIT and Harvard from my memory wasn't all that great looking, and MIT I only saw like one building of so I won't judge it.
NYU was waaay too spread around and varied to really even be considered...it wasn't ugly, just random buildings around that neighborhood, the library was visually impressive from the bottom floor looking up though...many floors.
So anyway, from all the colleges I've visited I actually think my own college is decent. The academic quad can look very stunning, whether it's frozen as hell or blooming with flowers...it looks great.
And the front of our library was done by the same guy who did the Lincoln Memorial =)