As of today (2021) I would say with no doubts that Julia _is_ the best alternative to Matlab, as for a very similar (but not, and not aimed to be equal) syntax brings modern designs, computational efficiency and already more "toolboxes" (packages) than Matlab.
The only exception for me is if one wants to retain the maximum source compatibility, then Octave could also be considered.
As of today (2021) I would say with no doubts that Julia _is_ the best alternative to Matlab, as for a very similar (but not, and not aimed to be equal) syntax brings modern designs, computational efficiency and already more "toolboxes" (packages) than Matlab.
The only exception for me is if one wants to retain the maximum source compatibility, then Octave could also be considered.