I prefer spd pedals with the cage around them like this (note, I don't actually spring for xtr):

because the shoes are walkable, I have a fairly wide platform and, if I am just going to go a couple of miles with the family, these are comfortable enough with just running shoes, so I don't have to swap shoes for a little jaunt around the neighborhood. I used to have the one sided spd pedals because I thought they looked more appropriate on the bike (and eliminated any possibility of pedal strike when I really aggressively cornered), but I always had problems with the wrong side being up when I wanted to clip in in a hurry (traffic, etc.). This style can cause pedals strike if you're pedaling through a corner and are tilted pretty far over (and run 175 mm cranks like I do - might not be a problem with shorter cranks and to be fair, I only had it happen a couple times), but I just either don't take the corner quite as aggressively (I am getting older so this is smart), or just coast with the inside pedal up if I'm leaning the bike that far.