Unless you are planning and can shoot very well beyond the 6-800 mark, you will be better served with the lower power variables. For decades, we hunted with 3-9x, 4-12x's and a few 4.5-14x, and still for most of my elk hunting, I use the 4-12 and 4.5-14x. My 890yd bull was shot using the 4.5-14x, and I have shot numerous 5-600yd coyotes and P-dogs with a 12x. Of course I do have several rifles that wear 5-25, 6-24, 8-32x and even a 10-40x, but most of the time, I have never used the top of the power range for elk nor deer.
That said, I give my vote for the 3-18x as one of the best suited for 99% of all elk/deer encounters.