In 40+ years of waterfowling, I'm certain I've killed hundreds of geese ... Canadas, Snows and Whitefronts mostly, from dug pits, blinds, over water and from layout boats, in at least 5 Provinces, with everything from Model 12's and 101's, a SX-1, an Ithaca 600, a borrowed Perazzi Mirage, Browning Superposed & Citori's, Remington 58, 1100 and 11-87's, a Beretta 409, 682, 686, DT-10, and 391, a Classic Doubles, an AyA, a Grulla, an A.H. Fox and a Parker amongst others.
My "go to" is still the venerable Remington 870.
If I were to "specialize", I think I might turn to the Beretta Extrema with KO.