the notch is preferred if you will mainly be cutting thicker items, because it allows you to pinch them closer to the bolt cutter's hinge joint. That allows you to achieve higher cutting leverage from your hand squeezing force. If you will not be cutting stuff that is on the thicker range of the bolt cutter's capacity, regular jaws will usually work better because you won't have to hassle with keeping smaller items out of the notch in order for them to cut properly.