this is a fantastic debate and I'm excited for it to play out. For the record, I think all 3 of those records are classics, all 3 are so different and show how versatile West is. College Dropout is more a pure hip hop classic based on the production, the album's flow, and the lyrical content. Late Registration had more of Kanye tapping into that pop sound (not in the sense of something like Justin Beiber or the like, but in the fact he worked with Jon Brion on some it and whatnot; a lot of strings a lot of baroque influence, etc.). MBDTF is more of the man going deep inside his psyche, matching production with the content - being grandiose as well as vulnerable. It's like a rock opera, it's his The Wall or Sgt Pepper's, etc.
I personally rank MBDTF as tops, but I can see and understand the arguments made for his first two albums.