I have owned and shot only Leupold for over 30 years but for various reasons, have just bought a Zeiss Conquest. I think I can give you a pretty fair comparison between the two brands.
Zeiss: To me the Zeiss has superior image quality (although the VXIII is very close). The Zeiss however is more crtical in eye relief. That means that in a hunting situation, when you throw the rifle up quickly, the "sweet spot" where you get the full field of view is harder to find.
Leupold: My Leupold scopes are in general, very good optically but not quite the equal of my Zeiss. However, the eye relief is less critical. When set at equal power ranges, when you throw the rifle up, the Leupold is easier/quicker to find the "sweet spot" If weight matters to you at all, the Leupolds are generally lighter.
For me, what this all means is that each scope has its virtues and each has its faults. IMO the Zeiss is the better optical instrument by a small margin. The Leupold (MAY) turn out to be a better hunting tool.
JimF
