After using many various sizes and styles, this is what I use. It may look like it can't hold much, but I carry much more than I need (4 knives, cleaning materials, rain gear, radio, water, lunch/snacks, GPS, 30 spare rnds of ammo, etc..). Not too big, not too small.
http://www.sportsmanswarehouse.com/s...0827/cat118605


I also keep a Kelty cache hauler freighter frame on my ATV but don't carry it with me while hiking until I need it. It has a stored blaze orange "rain cover" I can use to cover the meat and broadcast that I'm a person moving through the woods, not an elk.
http://www.sportsmanswarehouse.com/s...2545/cat100861