The Prostaff is a step down from the others in that group and I wasn't overly impressed by the Redfield
+1. I agree, the Nikon Buckmaster is probably the right scope for this group. The Prostaff is outclassed by the Burris and Vortex. So's the Leupold VX-1; the VX-II and VX-2 belong here.
I still think the Diamondback is the class of the field here. The extra 20% field of view over the others sealed it for me. At 3X, the Vortex has the same FOV as most 2X scopes. More FOV makes getting on target so much faster and easier.
And here's another ranking list for what it's worth: pe-scale-discussion-thread-2009_topic16515_page1.html