I use the spd on with tow way pedals (platform one side/spd other) for my utility commuter. The spd gives good walkablity.
I use the spd-sl (105) on my road bike. I tried the speed play and did not like them. for me they were not easier then the spd-sl and were a lot fussier with the big platfoms and having to put covers on, needing to lubricate every ride (per instructions) ymmv
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Life is too short not to ride the best bike you have, as much as you can.