Study both of them !
However, I perfer MATLAB, if I don't have enough time. Because it is so powerful that I can do other things with it besides IC design.
I think it largely depedends your application. Both of the software are the tool for our design, we must realize that software and simulation tool are used to verify our design. Throught this we can know whether or not the design is the ultimate idea or whether it is the requirement.