And that tends to be the problem we are seeing, cheap product with fancy features that delivers poor optical quality.
Who cares if it has side paralax, target turrets, some fancy sniper reticle, if it won't focus or has critical eye relief at max power?
Any scope that has a 4x or higher adjustment range ie...4-16 or 6-24 requires extremely high quality glass and extremely precise construction. Otherwise you will have basically unusable high power range in the scope. Only Japanese/US/German made scopes have that down pat, but expect to pay well over $1k for an entry level model.
Any lower or mid range scope stick to a 3x power range and usually it be ok...
I wouldn't compare the Viper line or Sightron to Nightforce..... More comparable to Bushnell Elite series IMHO, which they tend to be overpriced compared to in that case.
In good light I compare my PST to both the 50 and 56mm NXS all the time, even the ATACR, and it's not all that bad. By all the complaints I must have a very well built PST because I can see metal shot hits at 1000yards no problem and bullet holes in paper at 300y easily. The NXS glass in comparible light is not massively better. Sightron is on it's heals. Where the other two excel is eye releif and edge to edge vision. On a different train of thought many pro shooters think you should have a shadow around the optics which proves your head is in the exact same spot every time. It goes back to the peep site days in theory and works. If my head can be 10 degrees off and 1 inch back, will the gun shoot the same spot? no. Set up your gun for yourself, give it to a buddy and see where the shots hit. I gaurantee it won't be zeroed.
In addition to this, how many people shoot 1000yards? I do, but I notice very few on here do yet say optics on certain scopes are sub-par. My targets at my "private" range start at 800 yards. I don't see my PST holding me up in optics at all. I'm upgrading to the Razor for ####s and giggles. I should have it in two weeks.
If you shoot low light conditions, then yes, you will see the benefits of a NSX / Razor / ATACR, etc, but for those who don't want or cant spend 2000-3000$ they don't need to. We are blessed with the most sun hours out of any Canadian city. Rarely do I go out on a day with clouds, yet I am out nearly every weekend.
Bottom line, if you don't want to spend $1850 on a entry level, sub optic NSX, buy the Sightron and you'll have an additional $850 to spend on shooting and quality rings/rail. The optics in good light are damn near equal to the NXS. If you can't or don't want to spend ~$1000 on the sightron, the PST is a solid option at ~$850.
We live in an age where everybody needs top of the line gear but never use it. Skill is learnt behind the trigger, not spending all your money on expensive gun parts and raving about your new paint job on your stock. Be aware, research, make your own decisions, allow money left over to actually shoot, and have fun.