I have not used the vortex defender mounts, however I have used tenebrex, butler creek, Homemade 3d printed ones, leupold alumina and AAD mount. AAD are my favorite however, I've broken all the different brands, especially a pile of butler creek ones. But at $8-10 a piece i usually just buy a new butler creek one...In fact that reminds me I need to send my tenebrex and AAD in for warranty. . I usually run both a flip cover and a neoprene cover.