I have had a ST-10 and now an SN-3 3-17. I have been behind every high end scope under the sun: Premier, Hansholt, March, S&B, ect. (Advantage of shooting competitions at TVP you get to see all the cool toys). Prior to buying my USOs I had SWFA fixed power scopes which were nice but there was a point when I knew the downside of my score and weapon system was my optic. When this happened I started looking for an optic. Clarity at long range is king. Magnification isn't as big as long as your have good eyesight. I didn't think this was true until I was shown that even at 2200 yards when I looked at a target through a Premier at lower power I could still see shadows in bushes and around rocks. Looked at the same thing through my scope at a higher power and it looked like a kids finger painting.
Thats when I knew I had to save up my coin and get a higher end optic. The biggest advantages the USOs have over some of the others are the ability to build your scope exactly how you want it, and the fact it's tougher than heck. Those are the two things in my opinion it has over any other brand. On clarity this item is 100% debatable but I think my scope is on par with almost any other of the brands listed above and sitting side by side it is easily better than a Leo Mk4 or a NF. Two options I would highly recommend in purchasing a USO is the EREK knob (kind of a pain to zero but once you do you have 100min of up travel and a zero stop almost anywhere in the zero range) and internal bubble level. This is king when trying to make fast follow up shots using hold over in wind.
Regardless of the brand FFP is also king in my opinion because always knowing your sub-tense are dead on no matter what the power range makes follow ups and corrections extremely fast.
Good luck,
Merritt