My thoughts (owning and shooting both of them):
Sightron: Much better image at 50x mag. Less milky. More light. Rangefinding at very close and very long distances is somewhat more difficult. I need more foward-backward turning on the sidewheel to rangefind at 45 - 50 meters. And I use an close focus adapter under 12 meter.
Nikko: Easier range finding at long distance (45-50 meters). More defined from sharp to blurry. Better rangefinding at very close distances (<12 meter). Does not need an close focus adapter at the max magnification.