With that application, I'd go VX-6.
Target shooters seem to prefer Nightforce with its toughness and great tracking.
I think the VX-6 glass is better and the VX-6 is lighter and more streamlined. Hunters generally don't twist as much as target shooters, and my experience with VX-6 tracking has been great.
I also like the VX-6 duplex, thinking its the best out there for hunting. The VX-6 eyebox is the best I've used, and yes, I've used Nightforce.
IMO, others will have their opinions. That's mine.
DF