Leupold tends to have better resolution in their scopes than Nikon, and thus Redfield Revolution scopes are good quality. The Nikons tend to have better light transmission and color fidelity. There is an optical "triad" that exists that describes how companies design their optics. Take for instance the way that Nightforce has superior light transmission and resolution, but their color fidelity isn't as good. Leupold on the other hand focuses more on resolution and color fidelity for their Mark 4 scopes. This is why Nightforce is superior to the Leupold Mark4 series: they appear to be better optical quality because of the image quality in more varying light conditions.
I bought my dad a scope for his .308 rifle he bought for hunting. I tested the Leupold VX-II next to the Nikon Buckmaster, and I selected the Nikon because it was less expensive and about on par optically. The Nikon was brighter, but the Leupold has an edge in resolution. Since my dad wasn't doing extreme long range shooting, resolution was not as important as light transmission. You can select your optics to match your needs or desires.
Weaver tends to lean towards light transmission and resolution with their scopes.
The Leupold Mark 4 series is nice, but USO and Nightforce are significantly better for both optical quality and durability. We just ditched a Mark4 LR/T 3.5-10x40 and 4.5-14x50 for two Nightforce NXS 3.5-15x50 MLR scopes for our sniper rifles. There was a decided advantage of the NF over Leupold. Leupolds are good, but you need to go the 34mm tube Mark4 ER/T 6.5-20x50, Mark6 or Mark8 series to get decent glass (they have different glass and coatings than the 30mm Mark4 series). Even then, Leupold managed to jack a lot of stuff up with those scopes.
If you like the Mark4, you can get a Vortex Viper PST for about 44% less. Optical quality between the two is almost identical.