roosiebull
WKR
any brands you are looking at? if so, i bet you will get some good suggestions on options from those companies. i personally like the stryker xl or EXO 3500 (or their newer 3200) most packs cinch down pretty well if you want to buy one bag and have multi purpose. i day hunted and am currently using my gnargali for calling lions which is all day hunting.I am not worried about brand more interested in day pack size you guys prefer? Big enough to handle enough gear for a surprise possible night in the backcountry but not an extended stay.
if you were looking at seek outside, you could get a big huge bag with no weight penalty, compresses down to nothing, and would work for most anything.
for a dedicated day pack, i think 2-3000CI is a fair ballpark, though i have done a lot of moderate weather day hunting with an 1800CI pack, but as it gets cold, or packing my foxpro, i'm strapping some clothes to the outside, which isn't a huge deal.
it depends on a lot of things... what you're doing, the temps you're hunting in, and what you want to have with you.
i'm a poor packer for day hunting, i carry way more than i need, and day hunts, minus weapons, my day pack weighs 24-37# depending on the day and what i'm doing. i have never felt short on room with the stryker xl, and when meat hits the ground, it's quick and intuitive to load meat