All of my shotguns are 40 years to over a hundred years old. I guess my favorite is my J.P. Sauer 12 ga side by side. it's taken a lot of pheasant and quail over the years. As far as autos go, it hands down one of Browning A5's.
Another favorite of mine was made in 1898, it's a Charles Lancaster 12ga side by side. I love to take it dove hunting, and sit there and remember that more than likely, the first owner of this old British gun, (I think it says made in London on it), was probably shooting driven pheasant with it, before or slightly after Teddy Roosevelt made his famous charge up San Juan hill.