I've gone with 4.5-14, 4-12, and 6.5-20 scopes. I've got 4.5-14 on both my "long range" rifles right now, and a 4-12 on my varmint rifle. My everyday hunters tend to wear 4x or 3-9s. I do have one 2.5-10X Bushnell Elite 4200 that I like really well - it lives on my .25-06.
Anything above about 12 power makes mirage difficult on warm days, (but does help dope wind that way
), and I prefer AO or SF on anything above 10X. Side focus is much easier for me to use since I can more easily reach the knob than reach up to a ring on the objective.