mattri: A really big advantage for me with a variable power is the ability to reduce the power ( to 12x with my NF's), quickly find my very small target downrange, with the advantages of the wider field of view at the lower magnification, line up the rifle, front and rear rest, then increase the magnification to whatever I'm able to use, based on mirage & lighting conditions.
That's something you cannot do with any high magnification, fixed power scope.
I have several of the Leupold Competition Series scopes at a fixed 40x, and for that limitation alone, I must limit them to 300 yards maximum. In some of our match's we must fire at multiple targets, at various distances, with time limits included, so the faster you can find your target, the more advantage you have.
With the 42x, depending on conditions, I'm sometimes able to spot my 6mm holes at 500 meters, without having to use my Nikon 82mm spotting scope, another limitation I would have with a scope of lesser magnification, one of the reasons I say "forget about a 8-32x & get the 12-42x".
Whatever scope you decide on, get a good one with an unlimited lifetime warranty, like the NF, Leupold, Sightron, etc. And don't be afraid to buy used, if it's covered by a warranty.