I have a large collection of guns and have naturally tested them over a long period of time. At this point and, unless I'm going on a hunting trip, I carry one of two guns in the field.
1) 1892 Winchester carbine in .44-40 with peep sight. Reloaded with modern powers and jacketed cartridges you get 2000 fps with a 200 grain bullet.
That's more than enough to bring down a deer at 100 meters. For small game I carry shells using Speer plastic cups
I also carry a handful of .429 lead balls, a few primers and small can of Unique Powder with a powder measure. You would be amazed at how easy is to reload this cartridges with a light load. No tools are needed. This works great for hares, nutrias, etc. (No rabbits down here).

2) Rossi .308 single shot break-open gun. This is the gun that lives in the trunk. I carry a 10 rounds of soft point ammo for deer and carpincho and an adapter for .32 S&W and a box of .32s
That takes care of all the rest of animal edibles around here (which is vast).

This is what works for me, in my territory. Guns like clothes have to adjust to the area you are in. There is no universal gun for all purposes. The 12 gauge may be almost an all around gun whenever weight is not a concern. Try carrying two boxes of shells for a day and then tell me about it!