Depends a lot on personal preference and the distance that you will be shooting.
As for brand, I prefer BSA based on the cost vs quality. I've heard good things about the Nikon Pro-Staff.
As for the magnification, depends on distance to target; a 2.5x is sufficient in many cases but the 4x is more common.
The 3x9 is a good option. Set on 3x for quick acquisition and then change to 9x for the more distant shots.
A hunter should never use a rifle scope for spotting (for obvious reasons) but the higher power allows for confirming if a buck is legal after it is determined to be a desired target.
Another consideration is the width of the cross-hairs. The thinner they are, the more precise will be your point of aim.
I prefer 40 mm lens to avoid needing higher rings. There are benefits to mounting the scope as close to the barrel as possible. (line of sight vs line of bore)
Just look around, see what's out there and see what the budget can stand.
low power variable would be my choice (1x-4x) or there abouts.
I have a Pentax 1.75-4x24 ballistic plex and a Leapers 1.5-6x42 duplex tactical turrets,
both of those have enough power for any range shot I am liable to take.
I also have a couple of Weaver fixed powers 4.75x40 and a K6-6x38
Choice is usually based on price and brand loyalty, my personal favorites are Weaver & Pentax (more bang for my buck).
Other popular choices, Burris, Bushnell, Nikon, Leupold, etc...