I'm an amphibian: I have Look clipless pedals on my racing bike, and MKS Touring (plain) pedals on my commuter. I find that foot retention facilitates spinning at higher cadences, as I often do on my "fast" road rides and during indoor sessions on my trainer. But on my commute I have other priorities, such as wearing footwear that looks "normal" and is walkable and appropriate to the weather. Some people will make impassioned arguments that clipless pedals are safer than plain pedals, or vice versa. I haven't found, in my own experience, that either style of pedal is notably safer than the other (not, at least, once you're accustomed to clicking in and out of clipless pedals). There's one case in which I strongly prefer clipless to plain pedals, and that's when I'm on a fixed-gear bike.