All else being the same, a fixed power scope will be less expensive. I don't see how it can possibly be better than a variable scope of equal quality, though.

Cheap fixed scope is a cheap scope, and a high end variable scope will be brighter, clearer and more dependable than a cheap fixed power scope. Any scope, fixed or variable will need to be adjusted for parallax / or focus at various ranges if it has a power greater than 12.

What I am basically saying is I don't see anything inherently better about a fixed power scope, no matter what the circumstances are.