Clips give you a lot of versatility. If I'm just commuting or going around town, I keep them lose and they are like a platform pedal. If I'm doing the distance or stumping the hills I can tighten them up for maximum performance.

On a bike I have power grips on MKS quills but I'm putting clips on those as well. The power grips are ok but not as easy to reset; changing shoes often requires you to pull out the tool kit to readjust the strap.