Mil-XT if you like the grid-style reticles and Mil-C if you prefer a clean/more traditional reticle. Personally, I love the MIL-XT in my ATACR and would be hard pressed to go with a different grid system in my glass.
The Horus features are nice, but not really needed for 99.9% of shooters. If you're shooting movers, you should know your mil hold. If you're shooting and compensating for wind, you should know your wind mil values/holds. By knowing those, there isn't a difference between having extra/predetermined dots in your reticle and knowing it in your head. But that's just me.
Go Mil-XT and you won't be disappointed with the reticle.