The key difference is in terms of the database used. While SAS is useful in the case of metadata and SPSS is good for analysis; QlikView offers quite a simple visualization that matches MS Excel filtering.
When comparing QlikView with the other two, it is the most user-friendly and the fastest in terms of generating diverse dashboards/templates.
In terms of calculations, advanced statistics options are limited in QlikView.
For market research and analysis, SPSS has direct facility algorithms.