Both manufactures are turning out quality products. The difference comes in with USO as being more of a "custom" scope.
I find the customer service is top notch with both companies. Support is always there if you need it with both companies. Optically I find them too similar to distinguish and noticeable difference. All things I would say are equal except with the USO you have the ability to order a scope built to your specs.
I don't know if you would be using it for hunting or target, but the Nightforce velocity reticles
are nice for hunting purposes. Really nice for know distance steel banging too.
I don't know what lead times are running on USO but I know that these guys
always have Nightforce in stock whenever I call to order one.