I have riden a horse once in my whole life, and that was more than 20 years ago so what feels comfortable to me may not feel right to you... but this is what I do.

I'd consider myself right dominant (in that do virtually everything right handed and kick much better right footed at soccer). For me this means I want to push off with my right foot. I always unclip my left foot and put my left foot down. At interestions etc I'll leave my right foot cliped in and as the intersection clears or the lights change I'll move my right foot to the top of the stroke to push off.

Entering a potentially sticky situation I'll unclip my left foot, but leave it on top of the pedal, clipping back in once the situation clears.

I'd normally go many rides in a row without unclipping my right foot during the course of the ride.