444 Shooter,
Depending on your individual built you may need every bit of eye-relief you can get on that 338/378. My Zeiss Conquest 3-9 x 40mm has 4 claimed inches of eye-relief but Zeiss measures from the glass not the metal. If you get hit so hard that the glass touches you, buddy you've been smacked!

Actual distance to the eye piece is about 3.75" when I measured mine. The occular bell of the Ziess is significantly bigger and longer, which usually eliminates the lowest rings. It also means that eye-piece will protrude almost an inch farther back from the rear ring than a Leupold, if you need to move the scope all the way forward like I do. This is caused by the big housing needed for the quick focus eye-piece, and may not effect you. Basically I like the scope, but it lives on a .308 and will stay there.
The Leupolds are a little trimmer in dimensions and will mount lower. Most of their variables have an eye-relief of 4.5-5 inches measured from the metal. I measured mine. The eye-relief varies with magnification changes, which drives some people nuts, and bothers others not at all. I actually find it works in my favor. One thing that Leupold is famous for is their forgiving eye-relief. You usually have a good inch or so latitude in eye placement where it is "good enough". For a hunting rifle that will be shot with different clothing and positions this is a big plus.
Both have lifetime warranties, Leupold in Alberta, Zeiss in New York. Borders could be an issue if the warranty was needed. Chances are neither will break, so that probably won't matter.
Optically the 2 scopes are very close, with the Zeiss perhaps being a bit better. It's awful close either way, and both are better than they have to be for brightness. My 30mm LRs beat my Zeiss in this area, my 3.5-10s VX111s are close.The second is more an apples to apples comparison though.
Both scopes have slight differences and advantages. It depends on which one fits your needs better. Some things that might be a disadvantage to one guy won't matter to the next at all. If recoil clearance is an issue to you, then the Leupold wins on that alone.
I have just one Conquest, and an armful of Leupolds. Thats my "Wallet vote" for me, my rifles and my size and shape. The Conquest was a few bucks cheaper if that makes any difference.
Dogleg