For 35 mm I couldn't imagine using anything but the Hewes reels, but for 120 for me the winner is the design used by Kindermann: a spring clip that grabs hard or punctures the film right in the middle. Before getting a second-hand Kindermann reel I sometimes had problems with my Hewes for 120, not anymore.

It's still usually easy to load a normal Hewes reel for 120, however.