We have both available, but there are several riot type 870s out of the safe when we are home- and only one AR. Logic is, we both carry at home, but given the layout of the house we don't want to ever get cut off from easy access to a long gun. Entrances (front and back) are in the middle of the house, there's one bedroom on one end of the house and two bedrooms on the other end. So there are 870s stashed in hidey holes in all the bedrooms, but only one AR. That way we can't be cut off from a long gun, but if the threat is at longer range outside (we live in a rural area on about 20 acres) there's time to get to the AR.
We have no children in the home, and the guns go back in the safe any time both of us are gone. In addition, we have two Filas in the house unless we are gone for extended periods. That's 200 plus pounds of if-I-don't-know-you-I-don't-like-you. In the event of unexpected company that should prove something of a distraction to the intruder(s).
We use Federal LE132-00 in the magazines, with four Brenneke KO slugs in the Sidesaddles in case more range/greater penetration is needed than buckshot allows. I don't like #4 buck, as I prefer to push the buckshot loads out to what I consider the maximum range for buckshot- 25 yards and the smaller pellets loose oomph too fast to suit me. I expect to get patterns inside of a sheet of 8X11 notebook paper at 25 yards, and the Federal FliteControl loads will do it out of the CYL and ImpCyl 18"- 20" barrels on our shotguns. The shotguns here are fitted to my wife, and she can use them ably also. She's in her early 60s, 5'4" and 135 pounds but the properly fitted 12 gauges are not a problem for her. Neither is the AR, as she got sent to Louis Awerbuck's 3-day carbine class for her birthday a couple of years ago, and had run her own AR in 3-gun competition for years before then. We're not overly worried about ammo capacity either way, either long gun will do what we want. BTW, the AR here has two 20-round magazines on board, one in the magazine well and one in a pouch on the stock.
Clint Smith says the advantage of shotguns is that they can physically remove meat and bone. I agree, I have seen it done on the street as an EMT. I like shotguns, grew up shooting them, have a lifetime of experience with them plus some good professional training as well. I think there is no better defensive weapon than a good repeating shotgun, in trained and experienced hands.
I also think a person should use whatever firearm they are best/most confident with for home defense, no matter what that is- handgun, shotgun or rifle. Same goes for ammo choices. Whatever you want your firearm/ammo combination to accomplish, you should work to find what does best what you want done.
hth,
lpl