Been clipless since the mid 80's (still have my Keywins in the garage), but never commuted till this year. At first, I used my road bike and MTB with clipless to commute. When I finally broke down and bought a bike to dedicate to commuting, I did not think about it, I slapped on my late 90s era XTR spd pedals. I always hated toeclips, having to flip the pedals over to get my feet in and dealing with straps. That's why I jumped on clipless so early on. Had the Keywins, the original LOOK, the first Dura-Ace Look clone, the first LOOK Carbons, and Speedplay since the late '90s. From day one, I went clipless on the MTB.

So my opinions are heavily weighted to doing clipless if you are comfortable with it. SPD is perfect for the roll; I got some spd compatible shoes I can wear to work (thank G@d work is casual) and feel at home with that click when I put my foot down on the pedal. My feet don't slip off; I get good power transfer, and I can just hop off the bike and go upstairs to my office and no body knows they are cycling shoes.

Some of these newer plastic half clips look like a good idea (for clips, that is) but they are still clips. You still have to flip the pedal over, and they can get caught in stuff if you ride on the non-clip side. You still have to shove the foot in and yank it out, which I find harder to do than using clipless.