Shows good versatilty for the AR15 platform, 308 and can suppress-effective.
300 Blackout that is!
^^^This is fantastic!
SA M1A in .308 Scout with 2 X 7 X 32 Burris pistol scope. fast,deadly, reliable
Any AR from a reputable mfg should be able to shoot minute of pig.
.223/5.56 will be fine for putting them down. Many use it.
.223/5.56 will be fine for putting them down. Many use it.
On an AR platform, .223/5.56 is more than adequate for feral hogs. I would recommend using a heavier grain bullet, ideally around 70-75 grains. People kill hogs all the time with an AR and most hog culling from helicopters are done with AR's.
All the mfg's you listed are good, but I think Palmetto State Armory has the best deals right now on an all mil spec AR. Colt or BCM doesn't really have anything they don't. I personally like a 20" barrel in that caliber for the greater velocity, since I consider the 5.56 to be a little on the underpowered side for hunting that type of game... plus I still find it very light and maneuverable compared to, say a battle rifle... but people kill plenty of hogs with the carbines too so whatever floats your boat. Either way I'd go gov't profile or lighter on the barrel, since you will be humping it through the woods. I'd skip the heavy barrels unless you're using it for long range precision, or as a squad auto. 
I bet a Mosin Carbine would be pretty handy.
None of them, you need more cartridge to reliably take hogs, .243 Winchester should be minimum.
