It is not a real comparison to pitch a 50mm/1.8 against a kit zoom. Why ? Even in the film age, the 50mm's were the best made/designed lens in terms of sharpness, saturation, resolution, contrast. Simply put 50mmers were the best a camera maker could make. A zoom lens always has some compromises and will seldom be able to be best in some many areas. It is a no brainer if you have a choice and the focal length needs to be around 50mm use the prime it will out perform the kit zoom.