On MTB clipless/platforms are both double-edged swords for me. With platforms, I once in a while get bounced off the pedals going through bumpy/rocky sections at speed. But with clipless, I sometimes fall over in technical sections at very low speeds because I can't get my foot out in time. And often, approaching a technical section when clipped in, I'll give up early because the extra risk from being clipped in; but with platforms I'm free to try harder, because if I don't make it, it's easier to put a foot down.

I enjoy looking at videos and magazine photos of professional mountain bikers and checking out their shoes/pedals; I'd say nowadays they're about 50/50 clips/platforms.