see no reason for a fixed power, but if I had to choose it would be about 3x. My favorite power overall is 2-7, but 1-4 is better if you hunt in the thick stuff. I now have 2.5-10 and really like it, but all my guns do double duty for jackrabbits. I am never going to use 10x calling coyote. IMHO 500 yard dogs are mostly to make shows like fur takers interesting and sell you a bunch of junk you do not need. 90 percent of critters I have ever called in were inside 100 or so and 200 would be really far. Even in the wide open desert in an elevated position, they pop up in front of you after they slink through the depressions in the land staying out of view. With that in mind I say optimize for not only the most common distances, but also the shots you are most likely to hit. Is it worth missing 10 dogs at 100 with the hubbel on your rifle just so you can get one at 500? Finally, after 10x you really need AO. Whatever though, shoot fixed 36x and enjoy...