The ATACR is an amazing scope, but it’s a big unit! It has a 34 mm tube, so it may be physically bigger than what you were looking for. I’d sell every scope I owned if they made ATACR glass in a 30 mm tube. So until then I stick with the NXS. The 3 to 15 X50 is my hunting scope of choice. It’s not perfect, but it works well enough in most any circumstance you might face in the field, and it is dead nuts reliable. Personally, I was not as much of a fan of the 2.5-20 NX8. The eye box is really finicky and hard to get behind, at least for me. Maybe the 4-32 is better, But to me 30X is too much mag for an SFP hunting scope. Fov is just too tight.
I have no experience with the Leica you mentioned. Leica makes excellent glass of course, but I just haven’t seen enough reports for testing to their durability to give me the confidence I need to make a purchase. They could be bombproof, I just don’t know. Whereas, I know the nightforce is certainly up to the task.
Since you indicated you will be hunting off horseback, durability/reliability would be my number one criteria. In that case, rather than going down in endless rabbit hole, I’d find the nightforce with the specs you like best and go for it. You won’t be sorry and you won’t waste unnecessary time researching other options.