I'm right-handed, kick with my left foot, and always, always unclip the right foot when coming to a stop. Unclipping the left feels genuinely unnatural... to me. I've tried starting off with the right foot clipped in, and it's as if I've forgotten how to ride a bicycle.

That said, most people I see unclip the left foot at a stop. Which is weird to me here in the land of driving-on-the-right. With my right foot unclipped I can stand on the curb and stay in the saddle at stoplights.