Here keeping it simple is everything. You need to consider a few things, namely tube diameter which affects your rifle’s weight (for long hikes choose the most compact ones), exit pupil (in low-light conditions, keep the pupil 4mm above, and on a 2.5-10×50 the range is from 20 millimeters (2.5X) to 5 millimeters (10X), over adjustment is useless, mind your diopter (set it for your eye (look in your scope at a plain background not more than 20 feet) until the reticle is clear and leave it alone), parallax error is not a focus issue, choose FFP scope for taking advantage of the measuring opportunities of a Mil-Dot reticle and SFP scope if you are going to move it from one rifle to another, as for more flexibility.