I've used them all, spd most of the time. My bike is currently outfitted with the same Shimano pedal Machka suggested, a combination of spd on one side and a flat platform on the other. Next week, these pedals will join about three sets of spd pedals in a box reserved for components that I don't use anymore but which are too nice to discard. I'm going back to toe clips.

I have used toe clips for my last couple of tours and found them to be more agreeable than clipless. For me, they're easier to flip and slide into when accelerating from a stop. I don't have to "search for the click." I haven't noticed a significant efficiency difference between clipless and toe clips. I can still cycle in stiff soled cycling shoes during the day, but I can ride out for an evening's entertainment in shoes more comfortable and appropriate for the occasion and still have the toe clip to keep my foot properly positioned on the pedal. Toe clips permit me to ride without installing cleats into the stiff-soled cycling shoes, so now I can walk through museums, businesses, B&Bs or homes without the fear of scratching the floor or the "grinding" sound which can happen even with the recessed cleat.

I have had both a toe clip and the cleat on a shoe to break during rides. It was much easier to pedal with a broken toe clip than with a shoe that wouldn't clip into the clipless pedal.