I've done some bouldering and although I don't know what the actual best is, you don't want to land directly on your back or front (flat) and you never want to

I've done some bouldering and although I don't know what the actual best is, you don't want to land directly on your back or front (flat) and you never want to land on your head of course. I learned to try falling with legs slightly bent in a mostly upright position. Someone with more experience can give you better info though.