At close range < 7 yd (21ft) any 12ga load will be deadly, at greater distances it becomes less so. The larger the shot the more effective it will be at greater distance. If one is making a choice to prepare for a defense situation my personal choice is a lead BB load or heavier up to 00 Buck.

If the BG is kicking in the door and all you have is a box of #8 trap loads then that's what he'll be shot with and its a lot more effective than a baseball bat.