I respectfully disagree. I also have both and comparing a Nikon Monarch to a Leupold Vari-X III puts the Leupold to shame. In fact, when I received my Leupold Vari-X III 3.5x-10x-50mm Illuminated, I was disappointed.
Now, the Nikon Buckmaster is essentially the Pre-Monarch scopes - of which I own a few, and of which all of them have never let me down.
The Buckmaster to the VX-II is a good comparison, but the price difference is significant, with the Leupold (not surprisingly) being much more expensive. If you are going to spend the kind of money that Leupold wants for it's VX-II, you are better off, in my opinion, getting a Nikon Monarch.
Zachary