Old Tom Morris
HS Colt
Alister MacKenzie
CB MacDonald
I tend to agree with more of the old guys being on the list, given our current top designers are inspired to do work like them, rather than something really new, futuristic and dramatic. How can a generation of admitted copy cats claim to be better than those they copy?
Of course, under that theory, of the modern architects, IMHO, it was Pete Dye who really was a paradigm changer, should probably get on the list somewhere. As much as I admire Colt's work, he would probably be the one to go off, unless you figure his work, in a similar era and style as Mac's was superior to the good doctor somehow.
Given how little CBM was copied, even in his own generation, it could be him as well that I would replace with Dye, even if he coined the term gca, at least in America.
But, all in all, just a good fun debate with no right answers.