With respect sir, the OP didn't specify a static breaking situation where you set up the target exactly as you want it. Without a correct striking angle or on a curved target (like skull) where you don't hit it just right because the target is moving too, a broken hand is a needless problem in a fight, and potentially a big one. I believe that it's wisdom to be cautious about risking injury, not fear.
When I evaluate 'strongest hand technique', I'm looking first for practical use. I think it's wise to train the hand for the punch, but if I had to choose one or the other, palm heel gives all the benefits without needless risks.
Carl