Re: IOR 3-18x42 35mm
Disclaimer: I am biased. I own an IOR.
Personally, I think the glass in the IOR is superior to NF, though I have not looked through an F1.
I haven't used a NF scope, but when I looked through one, I wasn't blown away. It was good, crisp, clear glass but not in the same league as my 3-18.
I also thought the reticle was too thin for a tactical rifle, but that is just me. The fellow that owned the scope no issues running it.
You won't touch a FFP NF for 1500, they also offer a new illuminated reticle for a bit more.
The 3-18 works very well for me, some folks have issues with obtaining the correct eye relief. For more flexibility check out the 3.5-18.