That's a tough one. I guess considering personal defense, possible meat on the table, plinking, and somewhat for conversational value, I'd have to go with my Colt New Service. It was made in 1918 and originally sent to the Brits chambered for .455 Eley. I've since converted it to .45 Colt, which to my mind is pretty versatile when it comes to reloading for differing purposes.
Jim
Jim