Either one will kill a deer and a pig. It all comes down to which one you like, ammo supply & cost and which name of the cartridge floats off your tongue better. 6.8 SPC II is built to perform from shorter barrels and is a good suppressed round, even at full loads. 6.5 G was designed to have better long range performance/accuracy from 18"+ barrels. If you're reloading, you do have heavy .277 bullets for the .270 Win to choose from for experimentation but lot's of hogs are falling dead to lighter bullets.
