Gee, depends on the gun. I have a Featherweight 20 gauge, Ithaca an older Model 37 with a 20 inch, fully rifled M87 barrel for sabots.
Using Winchester Partition Gold sabots at 1900 fps, this thing recoils more than my 12 gauge pump actions using slugs. It is more accurate, and flatter shooting (35 and 75 yards, 1 1/2 inch groups) although I do not have a rifled barrel for any of my 12 gauge guns. So in effect, this is not a fair comparison.
This was at a range only, I have never taken any game animal with the 20 gauge.
The longest distance I have shot my 12 gauge on game is 75 yards (once) using a single Brenneke slug. Considering it's use though with iron sights, it certainly (the 12) was accurate enough for the job at hand. My experience is extemely limited.