20ga without question!!!! Kills them farther than most people can accuratley shoot. The 20ga is basically a modern propellant 50cal muzzleloader in a plastic hull. I have 2, 20ga and love them. A Mossberg Trophy Slugster and a Rem 11-87 Premier. Both with a rifled barrel and cantilever scope mount. VERY accurate at 100yds without a question.
They are sighted in 3" high at 50yds and dead on at 125yds, 6" low at 150yds. Puts all 5 back in the box at 125yds.
And I own a Moss. Trophy Slugster in 12 and never use it. Kicks too much. Would rather shoot my ML.