I would only use MTB pedals for commuting, chances are your going to have to walk somewhere and it' embarrassing walking any distance further than 5ft in road shoes.
For MTB I've tried Crank Bro's egg beaters, Time Atacs and SPDs. I like the crank bros the best because there ridiculously easy to get in and out of and they have alot of float.
Spds have a firm click in sound that lets you know you're in which crank bros don't.