Best choice (in my opinion)
Pistol length, rifle caliber(I prefer 300 blackout) is my recommendation for most lopsided(in your favor)home defense. Rifles(with appropriate ammo choice) and a good reflex sight are MUCH MUCH MUCH easier to bring on target and followup shots are similarly faster and more accurate than handgun. Also each round that hits is FAR more devastating to the threat than their handgun rounds coming back at you. Doesnt really have to be pistol length but I prefer it for maneuverability indoors. This is my 7.5 inch 300 blackout AR pistol on the bottom...for comparison on top is standard 16inch 5.56 AR rifle, and my springfield xd9 subcompact(3 inch barrel) with lasergrip(that I often carry concealed). The 300 blackout round is designed for full power out of short barrels(9 inch is optimal) and having 30 rounds of devastation to accurately send to any threats more than likely will provide me SUBSTANTIALLY more power in the gunfight than the invaders. I bought the 300 blackout pistol from Palmetto state armory for $500. optic(sightmark M spec FMS reflex) was around $200, and the light was $50. magpul angled front grip was $40. the ammo is not cheap though...cheapest practice ammo is around 50-60 cents per round. The good stuff for defense will run you over $1.00 a round...but if you need it...you will be happy you have it. Also you can add a suppressor and still keep a relatively short overall length and have the benefit of not destroying your hearing when you shoot it in your house without ear protection. That pistol is also small enough to ride in a standard gym bag so through it on your front seat and roll out(for those who can carry a pistol concealed) Here is 300 blackout through ballistic gel
How you like those sights?