I'm a big fan of MTB pedals for commuting. The shoes' lugs covering the cleat lets me put my foot down easily at long traffic lights or even a stop sign. You can get shoes with stiff soles for MTB pedals, such as my Sidi Dominators, that are pretty close to the best road-only shoes for transmission efficiency. And of course, no worries about figure skating, or losing cleat covers, when I get to work and walk up to my cube.