if you own either or both I'd love to hear your experiences

I would recommend the Leupold, The Nikon does have good glass but they has been a few issues lately over quality and warranty. With Leupold you are getting a solid scope and outstanding warranty if something ever goes wrong. I think that the VX-2 is a better option than the Mark-AR, same glass, basically the same scope, I prefer the smaller turrets and use known holdovers, than relying on a BDC that was calibrated for a different bullet than I shoot.