For the heck of it, I grabbed seven 35mm cameras at random and dry fired them:
Exakta VX1000 (left side front release)
Exa 500 (left side front release, slightly different design)
Praktica IVF (right side front release)
Mamiya Sekor 500 DTL (conventional)
Nikon FG (conventional)
Zorki 6 (conventional)
Leica IIIc (conventional)
Very unscientific comparison, but the Leica won out based simply on the smoothness of the release. A release that smooth could be anywhere on the camera and work well. Surprising second place was the Exa 500. Besides the release being on front, the "chunky" design of the body helps making a smooth push. It nestles in the hands. An underrated design, that one.
My conclusion: a well-engineered smooth release is as important or more important than the position. FWIW.
(yeah, I got a lot of cameras sitting around here....)