Compare them side by side and you will notice that Nikon has better optics in their mid range Buckmaster class of scopes than comparable Leupold Rifleman scopes.
I like the Nikon Buckmaster on field gun as the turrets are low profile but still feature 1/4 MOA finger adjustments marked in 1 MOA increments under the caps.
Nikon also offers a BDC reticle that works well for larger Coyote sized targets when you don't have time to make any sight adjustments.
I use a 4.5-14 Nikon Buckmaster with a BDC reticle on a 16" bull barrel carbine. It is a nice compromise between precision (will cut 3/4 to 1 MOA groups with fur friendly FMJ bullets all day long) and portability as it is significantly shorter and lighter than a 20" AR varmint rifle. The 4-14X Nikon also has a side focus/parrallax adjustment knob. It is quicker to use than a scope with the parrallax adjustment on the objective as you can see and adjust it without changing your shooting position.
But...if I am in a situation where I have to carry it a lot more than I have to shoot it, I prefer to take a pencil barrelled SP-1 with a 4 X scope.
I don't agree with the argument that a non adjustable objective scope is preferable to an adjustable objectivescope in scopes of the same power. A non adjustable scope will have the parrallax adjustment defaulted to 100 yards. However with an adjustable objective scope if you don't think you will have time to mess with the adjustment, you have the option of just leaving it at 100 yards which will leave you no worse off than you are with a non adjustable objective scope. Plus you also have the option of presetting it for the anticipated engagement range and, if you have time, setting it for the actual range.
So worst case, you are never worse off than you are with a non adjustable scope and if the situation presents itself, you can fully utilize the precision of high magnification without parrallax issues. In my opinion, non adjustable variables are intended for deer and larger sized targets and are less than ideal for predator and varmint hunting. Also in my opinon, a non-adjustable objective scope capable of more than 9X creates many more problems than it solves so it you really don't want an AO, stick with 3 to 9x or less for magnification.