Northern Lites, Atlas, Tubbs, Red Feather and others use a type of torsion bar on the binding. Atlas refers to this as SLS or Spring Loaded Suspension. This allows the snowshoe to rebound up for quicker transition between steps. Another advantage is if you need to back up, the tail will stay elevated rather than dropping down as you lift your foot.
Some snowshoes, such as MSR and the older Sherpa's, use a free pivioting binding.
My personal prefrence is the spring loaded, but they do allow snow to be flipped up on each step.