Depends on what you like, really. I prefer the AR to the SKS by several orders of magnitude, but that may have something to do with the years I spent carting one about in uniform.
I think you can still get an AK for less than an AR, but I built my AR for not much more than AKs cost. An AR tends to weigh less, if that is a consideration for you. The cheapest (currently) ammo for plinking would be 5.45x39. Don't know if you want to shoot hogs with that or not. All things considered, if I were going to be close-range hog hunting with a semiauto, the AK in 7.62x39 would be a front runner, neck-and-neck with the AR, probably. You can get an AR in a 7.62x39 upper, and that would be an interesting rifle, for sure, but it's a less common variant, and less common usually means more expensive.
I got rid of my SKS. I was never shooting it, because it wasn't accurate enough to be interesting to me.