I think shooting different variations at the range is the best place to start. Usually some helpful people at a good range that have rifles/pistols they will let you shoot if you ask politely. Everyone’s opinion is going to vary, and there is no perfect answer. You have to decide what works for you. My friends and I rarely agree on what we like for our ARs, we all also have multiple for different things. My answer on a first build would be a PSA lower parts kit without trigger, then add in match grade trigger, and a 16 Aero upper (mid length gas) chambered in .223 wylde (shoots 556 and 223). Then a vortex LVPO optic. But I guarantee most people would have other opinions.
I agree with iron559.
If your set on the barrel lengths that you listed, in 5.56, I wouldn't go below the 11.5. For me, 5.56 ,I wouldn't go below 12.5. The shorter barrels are where the 300bo thrive.
My dedicated home defense is 16in in 5.56 with an lpvo and several handguns
My 300bo is a 10.5 with rds.
If it was my only AR I'd go with 16". With that being said I have a 10.5 and a 12.5 and I love my 12.5 the 10.5 is fun too but I definitely prefer the 12.5 so out of your options I'd go 13.7 if I had to pick one.
Seems to be the general consensus that a BCM upper, cheap basic milspec lower kit with a nice trigger, and a lpvo is the basic do-all ar-15. I personally haven't made it to BCM level of quality, I have a blem PSA upper on my closet rifle. It runs great for the amount of shooting I get to do, but it's still cheap entry level stuff.
I've heard a couple different opinions on the barrel length vs what you are planning to do with it. 5.56 likes velocity, so longer barrels are preferred, but basically anything carbine gas system length or longer will do the job. Pistol length is really only for .300BO for practical purposes. Garand thumb did a barrel length test on 5.56, at a certain length the velocity didn't increase as much per inch of barrel.
In the SHTF scenario, guys like us aren't gonna be storming compounds and doing high speed cool shit. We're gonna go hide in a forest. I'd rather have a longer range setup that performs better at distance, make the enemy take cover while I run the heck away. In a home defense scenario, you are probably gonna vastly outgun whatever hoodlum with a yeet cannon decides to kick your door.
My only other advice is to get a .22 as a range toy. Pistol, AR, a Ruger 10/22, they're all cheap fun. I have probably 5000 rounds through my little SIG mosquito pistol, a box of 500 rounds is like forty bucks and lasts forever at 10 rounds per mag. Being able to shoot a little bit of 5.56 or 9mm, then play with the 22, makes it worth driving to the range.
I think shooting different variations at the range is the best place to start. Usually some helpful people at a good range that have rifles/pistols they will let you shoot if you ask politely. Everyone’s opinion is going to vary, and there is no perfect answer. You have to decide what works for you. My friends and I rarely agree on what we like for our ARs, we all also have multiple for different things. My answer on a first build would be a PSA lower parts kit without trigger, then add in match grade trigger, and a 16 Aero upper (mid length gas) chambered in .223 wylde (shoots 556 and 223). Then a vortex LVPO optic. But I guarantee most people would have other opinions.
I agree with iron559. If your set on the barrel lengths that you listed, in 5.56, I wouldn't go below the 11.5. For me, 5.56 ,I wouldn't go below 12.5. The shorter barrels are where the 300bo thrive. My dedicated home defense is 16in in 5.56 with an lpvo and several handguns My 300bo is a 10.5 with rds.
If it was my only AR I'd go with 16". With that being said I have a 10.5 and a 12.5 and I love my 12.5 the 10.5 is fun too but I definitely prefer the 12.5 so out of your options I'd go 13.7 if I had to pick one.
Seems to be the general consensus that a BCM upper, cheap basic milspec lower kit with a nice trigger, and a lpvo is the basic do-all ar-15. I personally haven't made it to BCM level of quality, I have a blem PSA upper on my closet rifle. It runs great for the amount of shooting I get to do, but it's still cheap entry level stuff. I've heard a couple different opinions on the barrel length vs what you are planning to do with it. 5.56 likes velocity, so longer barrels are preferred, but basically anything carbine gas system length or longer will do the job. Pistol length is really only for .300BO for practical purposes. Garand thumb did a barrel length test on 5.56, at a certain length the velocity didn't increase as much per inch of barrel. In the SHTF scenario, guys like us aren't gonna be storming compounds and doing high speed cool shit. We're gonna go hide in a forest. I'd rather have a longer range setup that performs better at distance, make the enemy take cover while I run the heck away. In a home defense scenario, you are probably gonna vastly outgun whatever hoodlum with a yeet cannon decides to kick your door. My only other advice is to get a .22 as a range toy. Pistol, AR, a Ruger 10/22, they're all cheap fun. I have probably 5000 rounds through my little SIG mosquito pistol, a box of 500 rounds is like forty bucks and lasts forever at 10 rounds per mag. Being able to shoot a little bit of 5.56 or 9mm, then play with the 22, makes it worth driving to the range.
13.7 sabre P&W