Lists like this are great. They inspire conversation and thats a good thing. Here are my two cents. Prior to the invention of the camera, artists were pursuing realism in an effort to render their subjects as realistically as possible resulting in more commissions for the artist. I think it was Picasso who said the camera has finally liberated the painter. As a result of photographic technology sculpture changed from the likes of Rodin to Brancusi (I believe Brancusi worked as an apprentice for Rodin briefly) then changed again with Duchamps readymades and again and again over the years with Warhols Brillo boxes and Duane Hansons hyper-realistic work featuring security guards and tourists. I think there are alot of great 20th Century sculptors missing from your list, but lists like this are highly subjective as it deals with individuals tastes . Maybe a list of the 5 greatest sculptors of the 20th century would be in order.