I use a kelty frame with no bag on it,it has a pocket for a water bag and the wrap around wings with straps,the fold down ledge is perfect for supporting the weight of an elk hind quarter or a boned out deer.
It probably depends more on factors like type of activity, length of activity, and weight to be carried (ie the backpack needed for an afternoon hunt would greatly differ from a two day hunt) I personally use a small pack that hugs low on my back for hunting. For long trips I pack in a external frame North Face pack. The bag is removable from the frame, so you can haul items like firewood or a deer quarter or whatever.
i am mainly talking about large backpacks not day packs. I have used the same internal frame pack for years and have used it for backpacking. I was just curious what others have used. I have just slid the meat into the pack and away we went.
This pack would be used for backpack hunts and to get game out of areas that you can't get horses to.
The #1 question in my mind when deciding what pack to use is what it'll be used for. I can't imagine an internal frame pack when hauling out meat. Aside from the shape limitation, you'll very likely be stuck trying to get blood out of the fabric. Externals can't be beat for hauling meat because they're so versatile in terms of strapping an odd-sized object, and they're easy to clean afterward.
However, if I'm just lugging essentials around and not taking meat out with it, I much prefer an internal pack that moves with me better and doesn't make me feel like I'm strapped to a headboard.
I have actually found internal frame packs are awesome for packing out meat. Just drop the quarter in the bag, tieten the side straps and start walking. I have had elk, mtn goat, rocky mtn bighorn, moose and muley in my internal frame.
As I sit and glass, which is common for hunters out west, I have sort of quickly discovered something I never learned when I was younger.
In my youth I had enthusiasm and spirit. In my middle to advancing years I have creaky knees, arthritis, and I tire more easily than I used to. Where I used to sit on the cold hard ground I now look for that soft spot to sooth my tired muscles. That leads me to my tip.
Carry your soft spot with you!
In my pack I carry an air filled, ultralight, camping pad....