Aren't you putting the cart before the horse?

Mechanical engineers came long before computers. So your first question should be : "What kind of a mechanical engineer shall i become?". Search deep in yourself. What do you enjoy doing? Heavy fabrication like boilers ? Machinery like earthmovers? Automobiles?

Then you can look at learning the appropriate software.

It also depends on where you are located.

If you would rather play a guitar and are good enough, you may try your hand at that too

In searching for employment in the future, you will find that some companies require you to know particular CAD software such as Pro-E or Solidworks, and they won't consider you unless you know the software they are using. Other companies are less interested in your knowledge of specific software but care more about your engineering or design knowledge; as long as you know some type of CAD, they will assume that you can learn their particular software on the job. But this is not as common, unless you have several years of experience and proven successes in your field.

As someone who is just starting out, you would do yourself a great favor in becoming proficient in several CAD programs, as there is a good chance that you will be doing more drawing than engineering, to begin with. If you are comfortable with both Pro-E and Solidworks, that will substantially increase your chances of finding your first jobs.

Of course, there is much more to an Engineering career than just knowing CAD, but that certainly helps. Good luck!