The prime lens is a way of life, much like the choice of a vegetarian or dinning in at Mc Donalds and chowing down on a BigMac. Its not until you leave your comforts at home that you begin living.
I have owned several prime lenses, acquiring, selling, switching to zooms and back until coming to a unnerving conclusion. If I was forced, didn't have a choice or my wife lay down the law so ferociously and said I could keep only one, would it be a prime or maybe a zoom?
Primes arent cheap, costing more than their zoom counterparts and are far less flexible in the conventional sense. But its their worth which you cant place the $$ value on. My decisions aren't always rational, 4 weeks in Europe last year and all I packed was the Canon 5D mrk iii and the 85mm F1.2. They called me "crazy!", and said "what are you thinking, I could never do that!". Before judging my choice, I challenge you to buy a prime, mount it to your camera and use this as your only lens for the next 6 months (get your wife or dog to bury your other lenses in the garden if need be). Its not until you surrender to the concept of working with less that you start developing.
Zooms always have been and always will be optically inferior. The day a fixed F0.95 aperture zoom lens is made I will eat my words, but that's beside the point. I can sit here writing all day comparing sharpness, weight, vignetting, size, shape, colour, contrast and blah blah blah the list goes on but at the heart of the matter non of these characteristics will make a memorable image which is ultimately our goal.
A prime encourages a way of thinking, when you have to zoom with your legs (i.e. closing the gap by walking closer or trekking up the adjacent mountain) only then can you comprehend the wonder of a single focal length. The creative thought process and compositional challenge is what makes a prime so special. I can guarantee your images will be better of for it. It wont be long until you are crouching, hanging off trees and really pushing your own envelope looking for different angles. It's this process, the limitation of not having the luxury of zooming in and out, snapping and walking off that constructs the better shot.
Those who can do more with less, who are more resourceful and innovative will always come away with the better product. A prime lens in the world of photography is dead center in this way of thinking and breeds development. For me the choice is easy, the zoom is dead!! Its a creative choice and one I had to experienced before it clicked. But for now the choice is yours..... I challenge you to give it a try and see what you think.