I have been a Leupold guy for a very long time. Their no questions asked warranty is the best. You buy a bad scope - the cost is only to send it to them with an explanation. I dropped a rifle and 30 feet in rocky terrain and bent my scope like a banana and sent it back to ask for a quote to fix. I got a new one in less time than a reply would take. I understand that Burris has same type warranty but have not tested it.
Burris does, indeed, have a lifetime, no questions asked warranty. I recently had problems with one of mine that is over 20 years old, called Burris, they told me to ship it to them. They fixed it, gave me a good explanation on what the problems were, and sent it back, free of charge. If you shop used optics, go with one of the companies that has the life time warranty that goes with the scope, not the owner, and you can't go wrong.