I was looking at a nikon prostaff 3-9x40 for a .308. Is this a quality scope or should I go with something better?

If your rifle has a fair amount of recoil, you need a good quality scope. Recoil can off set the cross hairs in the scope or cause other damage. Cheaper scopes are not meant to take recoil. I had this problem with a 7mm Remington. I did a bore sight. The first shot was dead on. The second was way off. All shots were with the rifle set up in a rifle mount, set up on a table with a solid base. In my case, I emailed Cabelas, explaining what rifle, scope and set up I was using. I received a quick reply, suggesting several medium to high end priced scopes from several manufactures. My rifle has a lot of recoil. Going on a hunt of a lifetime, Alaska, Africa etc. one wants a top of the line scope. For normal hunting, try to get a good quality affordable scope. Good luck in your choice.

I personally would not go with a ProStaff on a gun with that amount of recoil.
I just put a ProStaff on my personal 10-22 and my sons youth Savage Axis .243 but that's where I would stop.
I have a VX-3 on my 7mm Mag and love it.

I don't know what these cost, but you get what you pay for. A $100. scope isn't much of a scope for a high powered rifle. $300. plus and I say you have a good scope depending on the brand.

I'd post this in the proper forum , for max info.