I have used Look, SPD, and Speedplay (currently). I have Speedplay Frog's on my hardtail and Zeros on my road bike. I have found them to be the easiest to use. Their best feature, as do Crank Bros pedals, is the two-sided entry, which, after you adapt to them, means you never have to take your eyes off the road when you clip in. The float on the pedals means no knee pain. And the Frogs can work as a recessed cleat if you can find a mountain bike shoe of sufficient size. My $.02 worth...