I think I've seen a pig shot and killed with just about every different pistol and rifle caliber available, and as said above, where they are shot is most often more important that what they are shot with. Many times I've asked to land next to a pig so that I could examine the wounds because I just couldn't except that I had whiffed that many times, only to find out that it took 5 or more hits to stop its movement. Other times it's a pull of the trigger followed by a roll in the dirt, and I've never flown with anyone who could hit a silver dollar moving 35 MPH while they too were moving 35 MPH repetitively, so sometimes you just get lucky and your bullet landed well. Larger calibers do help when you're sucking at getting lucky, but then again, I've seen some stuff that has caused me to never loose my respect for a wild pig. 300blk with subs is how we clear golf courses and residential developments when being quiet is the number one goal, and I'm confident in my ability and the round's ability out to about 75 yards to place a hit with stopping power ( I don't like chasing pigs or leaving them wounded for some kid to find ). I wouldn't push it much further than that if you're using subs and don't want to crawl through acres of brush to find your hopefully dead pig. Supers on the other hand are fine out to a couple hundred yards just like the other pig staple rounds from an AR.
Unless you're using a suppressor, just go with the hardest hitting round you can. Even with a suppressor they don't just stand there and let you keep shooting them. Whatever you choose, have something stronger than a subsonic 300blk for back-up, because I've seen pigs charge through shooters while they empty mags of subs into them. A 45 on your hip can come in handy, while a buddy with a shotgun and buckshot is even better.
Good luck and have fun.