The military issue 3 day packs are very well made if you can find one. The difference in quality is noticeable but unless you get lucky the real ones are expensive, $90-$100 or more. I have a couple that I managed to pick up at gun shows for about $25 each before prices got crazy. And the real ones are getting harder to find.
They are also on the big side, maybe bigger and heavier than most need for a day of hunting. After all they are designed to carry enough gear for 3 days. And the heavy duty fabric, multiple pockets and webbing add weight. They are tough, but to be honest I rarely use them anymore.
I use a daypack for a lot more than hunting so it is easier to justify the cost. I'm currently using either a Camelbak or Osprey daypack that came from REI priced around $100-$130. The Osprey is a little bigger and conditions dictate which I use.
I use this more than the others. Mine is in green
https://www.amazon.com/CamelBak-1105001000-Reservoir-Hydration-Charcoal/dp/B01L8JEY26/ref=sr_1_196?crid=21B5NMNONN4PF&keywords=day+packs+hiking&qid=1563501700&s=gateway&sprefix=day+pack,aps,143&sr=8-196&th=1
Some thoughts:
* You probably don't need as big a bag as you think.
*I like one with the ability to strap my jacket on the outside of a smaller pack rather than have the jacket inside.
* I like a bag that is narrow and tall rather than wide, makes it easier to maneuver through brush and carry a rifle slung.
*Too many pockets adds to cost and weight. Keep it fairly simple. In rough terrain the weight of the empty pack matters more than you think. Keeping the pack smaller also reduces the temptation to carry too much.
*Camo isn't important, but the soft fleece of some packs designed for hunting might not be a bad idea. I have one very small camo fleece pack that I use during turkey and archery season where the noise and camo might matter. It is a little small for colder weather later on and I tend to carry one of the others.