Re: By a wide margin; Zeiss
I compared the Zeiss Victory 8x45 RF, Zeiss 10x45, and Leica Geovid 10x42 side by side. I have also used Leica Geovid 8x56, but did not have the others to compare on that occassion.
Here are my impressions, but others' experience may vary.
Image quality for Zeiss and Leica are very simlar, but I felt that clarity and color were a little better for Zeiss.
Ranging accuracy is similar between the two, and essentially a wash. However, to range with Leica you have to press the ranging button to turn it on and then again to range. For Zeiss, you depress the button once, hold down and release. So, ranging with Zeiss is faster. The other factor is that in very bright light conditions, the ranged number display can be washed out or difficult to see for all rangefinders, both Leica and Zeiss. This is where Zeiss ranging button is nice, after pressing the button and ranging there is a slight delay until the distance is calculated and the number displays. In that brief pause, you can turn your Zeiss binoc RFs down to the ground or cover you lens to see ranged number more clearly.
Size and bulk advantage goes to Leica 10x42 over Zeiss 10x45.
Rubber coating is more rubbery and more “grippy” for Zeiss, and harder and slicker for Leica. I preferred Zeiss rubber coating.
The viewing lens objectives that “touch” your eyes are easier for me to use with protective lens or glasses with Zeiss. For Leica, I could get a comfortable fit and image without glasses, but had a hard time with glasses. Zeiss has more adjustments with objective cover hood and depth/length that allows for a more comfortable fit for me.
The Leica 8x56 does provide better low-light imaging and sharp image quality, but is significantly more bulky.
Zeiss also comes with ballistic program, but it is fairly weak. You can choose from a few different zeroed ranges with set bullet drop paths, and then choose the one that is closest to yours. However, it rounds MOA or Mil to whole number, and the gets data from set bullet drop ballistics graph. So it is better than nothing but does not beat or eliminate a good dope card or true ballistics program.
I ended up choosing the Zeiss Victory 10x45 for a little for magnification, but still reasonable size to carry in packing when hiking…and also for abovementioned reasons. Hope this helps you.