Depends on your POU (philosophy of use).
If you are primarily active within 100 yards you want either Iron Sights or an Aimpoint (PRO??? subject to change) style for quick acquisition. This also helps with riding in vehicles as the FOV is large enough to handle the speed and acquisition of target.
At 100 yards you are looking into a scope for the 3x-9x magnification to range capabilities. The are HEAVIER and slightly more cumbersome.
Anything beyond 150 would require larger objectives and magnification ranges.
Now here's what I chose: a leupold mk ar mod 1 (1.5x-4x) with greendot reticle. I found that it gave me the capabilities of a dot site at quick acquisition and riding around, yet gave me the magnification of a scope (though challenging at 100 yards) it is still more precise than a Iron Sight or typical red dot. [it is actually fun honing in your skills without all that magnification]
As for quality, which I'm adamant about, it is the most qualified scope for what you will spend. Yeah you can spend $150 on a scope an be in an ever wonder state if whether you should change it out. (Ncstar and barska are not something I would ever waste money on)
Price: $375+ shipping and tax
Mount: $~90
So for ~$460 you are getting the best of both worlds, quality glass and manufacture (redfield is the same as leupold, but lacks the green dot and other bells and whistles that leupold offers), and the lightweight characteristic necessary for varmint hunting; anything over 8-9 pounds is too much for a ar-setup as this.
If you are going for anything beyond 100 yards you should be looking for a bolt action, bull barrel, and blind set up with very high magnification.
Here is how my first scope idea went; too heavy, slow, and zoomed in for shooting from a truck or quick acquisition. Also Nikon was not worth the money in quality= tons of gizmos and gadgets but no dot and 4x-16x bdc600
Would not recommend as clarity was awful
