In this case, you have to go with what makes you comfortable and the ability of the gun. If hunting in mainly timber, i would go with the smallest possible that will still be useful on that particular gun. If out open, spend a bit extra a get a larger scope. If hunting deer, bear, hogs, elk, etc. I would have to say a 3-9 is more than enough. If you want to bust ground hogs past 100 yards on a regular basis, i'd up it to a 4-12 or even a 6-18. I own a couple 3-9x40 vx2's, a 4-12x40 vx2, and a 6-18x40AO vx2 and love every one of them. However, i would never put one of 3-9's on my 22-250 which currently holds my 6-18. I am a big fan of leupold, but you may also consider a simmons aetec. I recently had a gun (owned it about 2 weeks) with a simmons aetec 2.8-10x44 and loved that scope. As much as i hate to admit it, it was as clear, actually brighter, and as good that my all of my leupolds. If i had a pick a scope right now, i would probably go that route.