I'll offer an opposing (different) viewpoint.
AR is fine. However, I do not buy into the whole frangible ammo nonsense. There are some basic truths. One truth is that anything which doesn't penetrate walls easily, is a poor performer for self defense. Anything that's a good performer for self-defense, also penetrates walls easily. So far, there's no magic bullet that stops in dry wall, but will mangle the innards of some violent homicidal manic in your home. Make your choice.
Your #1 priority in home defense is defending your life. It isn't your priority to protect the neighbors from the 1:1,000,000 chance that a bullet might penetrate all of your walls, their walls, and hit them. Your priority is to neutralize the deadly threat you are facing right there and then. The threat that if you don't stop, is a 1:1 chance you are going to die. We've debated (on THR) dozens of news stories where a home defender shot through a door or wall to incapacitate an armed threat that was shooting at them first through a wall or a door. That's my view. If you feel strongly about keeping the neighbors safe, then ignore what I've said.
There's a lot of mythology on the net. A lot of the ".223 is safer in the house than a 9mm" is a steaming pile perpetuated by positions held by law enforcement that were later exaggerated on the web. There have been plenty of tests, military included - that show the .223 is a serious penetration threat. There's no getting around that. Both .223 and 9mm are dangerous. Reality is, ANY centerfire is dangerous in a home. Period. The .223's growing popularity in LE is a direct result of it's superior performance over 9mm, not because it is safer for Mr. John Q. Public. AR's are cheaper than MP5's. .223 is more effective than 9mm. It's a logical choice for police. God bless them. Police face many problems. They face criticism for becoming "militarized" and often do not adopt rifles like the AR-15, or choose a pump action instead. They have to create excuses or feel-good justifications to get certain segments of the public to shut up. One of those is that the switch to .223 will lessen collateral damage. Meanwhile, all the LE ammo out there is designed to maximize penetration! Go figure.
Yes, I really feel so much safer that an entry team is using .223 vs. 9mm. Oh yeah! Their bullets will only go through 5 interior walls instead of 6! Anyway, police face serious threats, many of whom are heavily armed and highly dangerous. Like those N. Hollywood bankrobbers. Had those cops had a single AR-15, it would have been over much faster. Everyday cops are busting down doors of crackhouses where thugs are armed with centerfire semi-autos. They need firepower like the AR-15. So do you. Don't get me wrong, I'm not blaming police, but instead those who take something that the police establishment says for special reasons, and then transform that into a universal home-defense doctrine for civilians. Bad idea.
By all means, go get those frangibles. The gun weilding thug in your home will thank you for it.
My personal HD gun is a Saiga (AK) in 7.62x39mm. I want simple. No lights, lasers or other crap on it. Just one control on it - the trigger. Reliable. Tough. And fires a cartridge that will penetrate walls, cabinets, furniture or anything else in my bullet's path toward stopping the threat. AR is fine too. Choose either the 62gr NATO for a mil load, or a 69gr load. If you have a fast twist, go heavier if you can. Keep it simple with the AR. Home defense distances are usually never greater than 12 yards. A set of night sights might be better than optics and gizmos - you're at point and shoot range. Spend the money on a reliable rifle. Some people buy el-junko AR's then accessorize them with $1,500 in rails, optics, BUIS and other useless stuff that serves no purpose in saving your hide. They don't have their priorities straight, much like those worried more about their neighbors. Spend as much as possible in getting an AR that doesn't jam, won't break a bolt on you or anything like that. Take care of the basics and essentials, then add stuff if it can help.