Should I learn AutoCAD or REVIT?
If you learn AutoCAD before Revit, you’re going to end up with all the bad habits AutoCAD drafters have, that don’t work on Revit.
Revit is a whole different mindset from AutoCAD, in part because it’s 3D, in part because you’re building a model (not just a drawing), and in part because there’s a whole lot of information attached to each and every element you model.
Learn Revit. And then if you need to, learn AutoCAD.
Well, as you have already heard about your question, let me explain the answer.
There are many options for 2D and 3D software on the market. If you study engineering and want to specialize in mechanics, SolidWorks can be interesting because you can, from the 3D model, study the structure of the part with SolidWorks simulation.
If you also want to learn 2D software, I recommend DraftSight, a free CAD software, where your paid version is much cheaper than the other models on the market. Yet, it has all the capabilities of CAD and applications to incorporate.