CATIA is the most essential software for a mechanical engineer. CATIA is the most popular design software, and companies across the globe widely use it. In contrast, ANSYS is more of a simulation software than modeling software. Whereas it is also good to study ANSYS, it will not play that much of a role in boosting your portfolio as a mechanical engineer. CATIA, on the other end, provides users with the opportunity to model realistic products. It is also good to note that CATIA is one of the most sophisticated software that we presently have in the market. If you can learn the system's ins and outs, this will give you significant professional mileage since your job as a mechanical engineer will involve a lot of product modeling. Another alternative to CATIA would be Solidworks. It is also a commonly used design software, and knowing how to use effectively would be a significant plus.