There are 2 common aspects about breaking and probably neither of them answers your question. There are 2 ways to do any technique: the proper way and the one that throws your whole body into it. If you use your body weight to break something, it's just a matter of getting your hand between your body and the board/tile. So, which technique allows the maximum body weight to drop? If you can do a proper technique, then which do you feel is more powerful? I use the word "feel" because obvious you know how it feels when you hit something. The other aspect is the weapon or tool used to break. Many people use hammer fist or knifehand (sudo) because of its padded surface--makes someone more fearless when they strike. Fists and elbows have hard surfaces and hurt more if the break fails. Part of this too is your willingness to accept any pain. My instructor was once asked if he could break 4 boards with his fist for a test. He said yes, it'll hurt for a month but he can do it. He didn't have to.