I'm just gonna guess the scenario was for a night time invasion...
Right beside the bed, and leaning up against the wall, and the headboard leg, is an SBR of the AR variety. It has an 11.5" Sig 516 upper with a Midwest Industries handguard. The Aimpoint Comp M4s red dot sight, provides near instantaneous targeting. Surefire provides low light vision and sound suppression with a Scout light, and a 762 SOCOM MINI2 suppressor. Trigger is a Fostech Echo AR-II, sling is Blue force, and the magazine has 30 rounds of the IMI 77 gr Razor Core. (MK 262 Mod 1 clone)
As asked for... there are reasons I chose this up.
1. The MK 262 has shown itself to be a very capable anti-personnel round. Exactly what's needed for home invaders.
2. The AR-15 has (since it was first developed in the mid 50s) evolved into the quintessential American defensive/sporting rifle. A shortened version (SBR) is even more handy within the confines of a home.
3. The use of a suppressor mitigates much of the blast that would be greatly increased by shooting a rifle indoors, while the piston driven system (Sig 516) helps keep the weapon cleaner, and cooler, especially when shooting suppressed.
4. Having a weapon mounted light allows for searching areas, making positive ID of threat/friend, and can also be used to disorient a threat momentarily.
5. The sling allows the weapon to be held by the body, while hands can do other tasks, and can greatly aid in a struggle for retention.
6. The binary trigger 30 rounds of quality ammo is, well, self explanatory. Anything worth shooting, is worth shooting twice... and quickly.
7. Most importantly, (and this is a biggie) the AR platform just happens to be what I'm most comfy with in my hands.
I spent 28 years in the U.S. Army, and have deployed to war multiple times with similar weapons. After spending half my life with one in my hands... the weapon system is just second nature to me.
It's what I'm best with. It's what I've used in battle to save my life before, and I have no doubt it would serve well in that role again if need be.
Anybody chooses a weapon for home defense should IMHO choose the one they know best. (be it rifle, handgun, or shotgun)
In that moment of fear & panic, you must react instinctually, and without pause. You will not have time to remember steps.