Spear would be bad ass, but those teeth are a little too big for me to get that close. Killed one with a bow when I was a teenager.
I've killed probably 6-7 feral hogs in Texas in the past. We either hunted them from deer stands or spot and stalk from pipelines.
We used real centerfire deer rifle calibers (not Indiana deer rifle calibers...LOL) from .243 min to 300 Win mag. If you use a .243 shoot for the head (ear). A friend of mine shot one in the shoulder, then followed up with a head shot to put it down. Upon skinning, the 75 gr. hollow point, hit the shoulder bone and it didn't punch through to the heart/lung area. If he hadn't followed up quickly with that head shot he would have run off. The .270 or 30-06 would have punched through to the heart/lungs.
Field dress, them quickly and properly and it will be some of the best pork you'll ever eat. I will make one caveot to that last statement, ocasionally you just get a bad tasting one. I killed a boar once which one of the "hicks" down there had captured while a shoat in a trap and castrated it. It was about 300 lbs and I cut off about 100+ lbs of fat., it was horrible tasting.