I don't have experience with other spotting scopes. I've used Leupold most of my life (64) but have used a Zeiss bino for about 10 years and have 2 Zeiss scopes I've used for the last 3-4 years . The Kowa seems to be the best optic I've owned up to now. It's not the "new" model but it's not the " new " price either! When I researched the web for hard information hunting sites offered little help. Bird watching sites have the best critically review info. At the time it was ranked #3 behind Swarovski and Leica. Find reviews and also look at Cornell's ornithology site.
Thanks for your interest,
Bob