Updated: Aug 8, 2019
The first question that pops up in anyone's mind , who is looking to learn CAD design software is, "Which CAD software do I choose? Which CAD software lands me a job?" The answer to this age old question is both simple and complex on it's own right. So let me explain this conundrum.
The simple answer:
If you are a beginner, this answer is for you. The simplest answer to this question is, "It doesn't matter". Whichever CAD software you choose, it can do all the basic work a beginner might need. So if you are new to this CAD world, feel free to experiment with the demo versions to get a better understanding of the basics and then decide to jump into it.
The complex answer:
The complex part of the answer comes into play, when you want to concentrate on a specific part of the CAD industry. But before we get into the answer, we need to understand the types of CAD software and what they can do, with certain examples to make us understand the situation. Remember that this classification is from the perspective of a mechanical engineer.
The above classification does not mean that they only work on their respective categories, but are best suited for the category they are placed in.
Autocad can be used to generate both 2D and 3D outputs. But it was built around drafting and thus its used for drafting as an industry standard.
CATIA can be used to do FEM analysis on mechanical parts. But is was built around 3D modelling and so it is categorized under parametric modelling. Eg 3:
Ansys has a module called 'Spaceclaim', which can do a good job in 3D modelling. But Ansys was built for analysis and so is the industry standard.
Thus the softwares in each category are specialized in certain work and its better we stick to them.
Now to that complex answer. It deals with the specialized domain of the entire design process that you want to get into. To be adequately knowledgeable, you have to have an in-depth knowledge in any one software of one of those categories and basic knowledge of any one of the softwares in every other category. Our suggestion would be,
(i) AutoCad for drafting,
(ii) CATIA/ Siemens NX for surface modelling
(iii) Solidworks/ creo/ Fusion 360 for solid modelling
(iv) Ansys for Analysis
Finally, the suggestions we gave above are just suggestions. Consider them if you are entirely new to this CAD design world. But if your requirement is centered around a specific CAD software, stick to that.