Here's my 411.
I just sold my 10x42 SS (here actually).
I'm trading up to a Nightforce NXS.
I really liked the SS. Clear Glass, mil-dot was true to specs, repeated back to zero when adjusting for elevation, and it seemed rugged though I can't say I ever beat on it, and it was fairly inexpensive.
Having said that, I wanted a high-end scope with more magnification. Something that I absolutely can be confident in. I always had a little bit of doubt about the SS's internal ruggedness--no real evidece of that, but it was just my gut feeling maybe due to the low price point it sells at.
So, after playing with a NF NXS, I decided to go with the true high end. NF just has some more features that I realized I would prefer (e.g. finer markings on the turrets for recording zero, higher magnification, turrets that feel like there are fluid damped yet are precise to no end, ultra-clear glass to aid my corrected eyes, and tank-like ruggedness).
I think a fair comparison is that the Tasco is like a Honda, no frills, light, gets good mileage and will run forever; and the NF (or S&B etc.) is like a Mercedes, heavy, vault-like, powerful, and Teutonically precise.
Maybe Jim_Dandy was right and I am a closet optics snob!