Exactly Sightron and Vortex have just as good of a warranty as Leupold, if not better. I'm not sure about Zeiss. Leupolds warranty says they don't have to replace or repair the scope if the damage is caused by the user. Now I'm quite aware they usually either do, or work with you and charge a minimal amount. However, with the warranty written this way, they could stop at any time. Vortex has their warranty written so that it covers the scope even if the user damaged it.

Nikon also has a lifetime transferable warranty. I'm aware that their CS isn't as good as Leupold, Vortex, Sightron, etc, but they still have a lifetime warranty that applies to anyone even without a receipt. I've never had to use their warranty though, so I can't comment too much on it.

Actually, Leupold is the only scope company that I've had to deal with the warranty department of.