I'm new to this board, but I thought I'd chime in here, since I have first hand experience with all of the rifles being discussed. The Mini-30 is a fine rifle, as is the SKS. The 7.62x39 round was designed for engagements within 300 meters, packing the most stopping power into the smallest and lightest weight cartridge. Any of the rifles discussed here are easily capable of 4 MOA groups if the shooter does their part. I am very confident in saying that, because I consistently do it while shooting at Appleseed Project QDAQT targets.
All of these rifles can use improvements, but that's true of nearly every rifle. For the SKS, Tech Sights and a trigger job make it an excellent rifle, and the Mini needs barrel stabilization, a trigger job, and adjustable gas pressure to make it also really good. None of these are tack drivers, they are not intended for that. They are all utterly reliable, and in my experience will eat just about any ammo.
For my money, though, the SKS is the winner because of the cost.