I am an unapolgetic Leupold-lover. I visit the Leupold plant often; the product and the folks are THE BEST.
There is no way I will ever personally own anything but a Leupold. In my defense, trust comes slowly for old farts like me. I've hunted at minus-30° several times with Leupolds. I've used them while riding mules and horses; I've used them on the hotter-than-Hell Kalahari where I friggin' near died of thirst (is a Rowland Ward gemsbok really worth it?).
I've owned hundreds of Leupolds and I've never had one fail; nor have I ever seen one fail, even while I spent eleven years guiding elk hunters in Hell's Canyon.
The Leupold will not fail and if readers call me prejudiced, so be it. I'm not about to gamble a five thousand dollar hunt (often more), just for the opportunity to use a different brand of scope.
OK, having said that, in my writing, I've tested two custom rifles lately that came equipped with Nikon scopes. In both cases, the Nikon scopes worked admirably; they were very clear and the adjustments were perfect. I would use one on varmints or predators and have no regrets.
On big game, where it really counts, I'd still use a Leupold, but that's just my opinion.
Steve