SPSS or SAS, which program do you prefer more?

To collect, integrate, analyze, and interpret vast data in bio-medical, social, economic and many other sciences, you extremely need to use an appropriate computer program. 

On the one hand,the software used has to provide perfect, more comprehensive, and precise results of what the calculations indicate . On the other hand, software designers and developers have to provide computer programs specialized in statistics easier, inexpensive, quicker, more available for researchers to use , otherwise you cannot manage complicated analysis using an appropriate statistical software.

Have you ever experienced using these kinds of statistical programs?What do you think about SPSS, STATA, SAS, and so on?