Being old fashioned, I still use walnut stocked O/U's, SXS's or classic pumps for my shotgun adventures. I'm the Old & Cranky Guy wearing the waxed cotton Filson or McAllister coat with a Chesapeake.
For waterfowl, a Browning Citori Satin Hunter 12 Ga. 3 1/2 version, however I seldom shoot the 3 1/2" shells. I also shoot an Ithaca M37 or a BPS; both in 12 Ga.
For pheasants and Huns, usually a 16 Ga. DeHaan SXS, BPS, M37, 50's era Wingmaster or M31 pump.
For Ca. quail or forest grouse, my current favorite is a Stevens Model 555 O/U in 28 Ga.; although a Weatherby SA08 semi-auto or CZ Bobwhite also in 28 Ga. see use.