The one Thing I like about the nikon prostaff or any other nikon scope is the Constant eye reliefe.... If you get a 3-9X40 prostaff, it has steady 3.6" eye relf..... which I think is great... also 90% light transmission is not bad either
I have a burris 4.5X14 and its a "good" scope, but when I shoot at 300 yard targets and my variable is set at 14X, that 3.1" eye relief bothers me a little bit, forces me to push my neck forward (more than I want it to be), its not going to hit me or anything, but it bothers my shooting style..... Thats why I just sold the scope to my brother last night, I just didn't enjoy the long eye relief...
When it comes to eye relf, Leupold and nikon are great (so is ZIESS but I haven't won the Mega millions yet)
So, IMO, when it comes to scopes, you should always buy one that has
1) full life time warrenty (no matter how good your scope is, sometimes it does take a beating)
2) good long eye relife, makes your shooting style comfortable, you no longer have to push your neck forward to open that view ESPECIALLY when you have no more room to move ur scope backwards.
3) good glass and Im not refereing to the best of the best, a prostaff has good class. Not as good as a VX-2 or 3, but it will do its job on a regular basis.