Neither. They are pretty much complete opposites. The I4 is very small and tight to your face, while the Proflex is bigger and well sits kind of far away. My Proflex also feels very soft and a little loose, while my I4 is a pretty tight fit. Both are incredibly light though, very comfortable, and give you lots of view. The only real downside on either is that the Proflex lenses are a lot more difficult to switch out.
Either decide which fit YOU are going to like best, or go try some on at a shop and decide there. Any paintball shop should have both masks available in their store.