if you are considering look or speedplay, your decision will probably be determined by your float needs. If you prefer less float, try the looks, if you want more float, try speedplay. I have a set of speedplay zero: adjustable float from 0 to 15 degrees.
Look does have a pedal with adjustable float, but I don't think it's true free float, and have heard that it doesn't really work. If you do go look, maybe stay away from these and go for the ones that take different cleats to change float.
All that said, I would probably go for speedplay (and did), cuz I like the float.
Dax