RE: Which gun should I use?
What range do you expect to be shooting them there hogs...??..
At ranges of 150 yards or less, any of the three would work fine..
If you are hunting big fields with long shots, use the 7mm mag..
At normal woods/brush ranges ( where I have hunted hogs) hit them in the heart/lung area and they will be very dead piggies very quickly with any of the three chamberings that you mentioned..