I prefer a side-mount tactical sling like the padded VCAS for hunting. This lets me carry the rifle slung across my chest in more or less the low ready position. This is more secure than shoulder carry, and makes it quicker to bring the rifle up to your shoulder. The "hasty" shooting sling method also works a lot better with this setup than it does with a standard shoulder carry sling. Since the sling runs over your back, it doesn't slide down your support arm; and with it being side-mounted, it doesn't want to cant in prone and seated like a hasty sling usually does. And nothing could be easier or quicker to get into and out of.
If I must use a standard bottom mount shoulder carry sling, I use a 1907. I leave the keepers up high by the front swivel, which leaves the arm loop open wide. For a quick shot in the field, you don't even need to put a twist in the arm loop or cinch the keepers down like you would at a match... just stick your arm through the loop, wrap your wrist, and shoot. It is just as fast as a Ching sling, and doesn't require the third swivel. In fact, the dude who makes the Ching Sling later came out with the Safari Ching Sling, which pretty much works this same way.