>>13866590I don't use either, but that's because I just like using R and most of my work is in statistics or statistical modeling.
For extensive use I'd probably use octave. I'd say Matlab if it didn't come with a price. I use Matlab occasionally at work because it's common, but again I prefer R and have been pushing my branch towards R for awhile (it really is the best for statistics).
Most people probably wouldn't be immediately able to recognize Scilab or Octave on your resume, so just make sure you're saying you know Matlab even if what you really know is Octave. This is also what I do with Python, even though I don't use it much, I'll say I know it well.
Really it doesn't matter which you pick. They're all really basic and quick to pick up as long as you know what you want.
