Many people, including myself, have thought that buckshot is better for home defense than an AR or pistol. My wife has a shotgun with buckshot for times I am not home. While researching the effects of buckshot, I may have changed my opinion on this.
There are a few pros to using a shotgun over anything else. Firstly, the pellets will not go through walls and potentially hit someone in another room. Another great thing about using a shotgun is you do not need to be as accurate due to the spread of the pellets.
The problem with using a shotgun is the effects it has on the intruder. I found X-rays of a home intruder shot with buckshot with his arms up. The X-rays show that the pellets did significant damage to his arms, but did not penetrate his chest head, or abdomen. If this intruder had one good arm he could fire back on the homeowner. While this will stop most people, It may not be enough.
There is no disputing that a shotgun with buckshot is easy and very effective, but it may not be the best choice for home defense. A handgun or AR15 in the hands of a trained homeowner is the best option.