The clipless peddles are much more efficient. Also they make peddles that are dual purpose. They have the standard pedal platform on one side so you can ride unclipped and the SPD binding (clipless) on the other so you can clip in. I like having the option when mountain biking because I don't like to be clipped in in more technical situations. The pedal is the Shimano m324 or Nashbar makes a version that is cheaper that I believe they call the Rodeo.