I'm going on a hog hunt in GA in the spring, was wondering the same thing. My sidearm choices are an 8-shot S&W 357, a 44mag 329PD, G40 and G20. I'm leaning towards the G40, since I'm going with a bolt rifle.
It depends on your size, build, and what game you are hunting. Shorter barrels are better for flushing upland birds and skeet. Longer barrels are better for Trap, passing waterfoul, tower pheasant shoots, etc. 28" is a good compromise if you have to choose one length for what you have listed...
I know of a deer shot with one by a friend of mine that turned a flip in the air after being shot and ended up with a wasteful amount of meat destruction.