I Don't know if this will pertain to you or not. Some people scoff at the name, but I recently picked up a 4.5-18x40 Bushnell AR optic. Turns out, it's a really great scope. The reticle is very fine and clear, fine enough to put my crosshairs in between 1/2 circles at 100 yards, something I was unable to do with the Nikon. The glass is crystal clear and I was banging out a 600 yards plate without fail on a cloudy day. The relief can be somewhat unforgiving on ma magnification, but anything under 16x was very easy to get a good view. Awesome turrets, slightly too tight yardage knob, but overall a really impressive scope. I grabbed mine for 150$ which was the norm a month ago, but appear all is over 200$ now for some reason. Mine is a .223 BDC, not useful to you, but not sure if it's .308 brother would satisfy your needs. I can only assume it's the same quality glass and components, just sporting a different reticle set-up. The reviews on opticsplanet, amazon etc are all outstanding and would heavily recommend over the Nikon ProStaff. I have no experience with the vortex, I only know they have built a great image for themselves very quickly, so one can only assume they make quality products.
but, as I said before, I do not know if a 308 BDC would be of any interest for your rifle, just thought that I would share that this is my third Bushnell Scope and have been pleased with all, and even the cheap Banner Series far exceeded my expectations and has lasted several years sitting atop Mosin Nagants and bout every other rifle I own, although I will admit the Banner's reticle is large and not suited for target shooting. But you may find a good value is Bushnell and I can confirm that they take a beating.
http://www.amazon.com/Bushnell-4-5-18x40mm-Riflescope-Dropzone-AR945184B/dp/B00UNO0ZDK
opticplanet charges an extra 28$ for the 308 over the .223
http://www.opticsplanet.com/bushnell-ar-optics-4-5-18x40-riflescope-w-bdc-reticle-matte-black.html
I am not sure if Bushnell uses the same glass etc for their more traditional type scopes, like the legend etc, but if so, I would assume them to be nice glass for your purposes if the tactical route is not useful to you.
http://www.amazon.com/Bushnell-Legend-Reticle-Riflescope-4-5-14x44mm/dp/B006UJ02Z8
the scope does have one "tick me off" feature, and that is the knurled magnification wheel which interfered with my 2-piece Nikon P mount, so had to flip the mount backwards and now scope is too close to the stock, I will need to purchase a new mount for future use.