Depends what sort of shooting you intend doing: Driven game, walked up, 'fowling, Grouse, high Pheasants, Clays etc. Recent articles in Shooting Gazette on shotgun choice, would help?
I used to get buy with an AYA 25 ss improved/modified 3 in Magnum proofed and varied the shells. I shot everything from driven partridge with subsonics to 200 foot high Graylags with AAA Gevelot Supervix. Kicked like a mule with heavy loads though.