Leupold is probably my all-around standard, I own four Vari-X II 3-9s alone - everything else are Vari-X IIIs and Mark 4s. Never a problem with any of them. While I'm also a Burris fan, I've had occasion to test the warranty when one of them failed. Burris replaced the scope, but it would still be preferable that the failure not have occurred in the first place. I've also collected a couple of Vortex scopes - which have been good so far, though I've only owned them for a couple of years now. My Nikon spotter failed me years ago. Although it too was replaced, the experience soured me on Nikon.
As important as your scope are your mounts. I tend to use the one-piece bases whenever possible, and from a reputable manufacturer.