For what purpose? Employability, intellectual well-roundedness, zeitgeistiness? Each of these could pull you in a different direction. My current hunch is that

For what purpose? Employability, intellectual well-roundedness, zeitgeistiness? Each of these could pull you in a different direction. My current hunch is that statistics/data science/machine learning will satisfy at least two of the above three, if not all. I've been learning the basics of data analysis with R, much helped by the awesome RStudio. Initially this was for fun (and a tryout of MOOCs, specifically Coursera's data analysis class) but after only a few weeks I found occasion to use it at work (finding patterns in an application's response times in response to user load throughout the day). Now I'm getting into stuff that's even more fun, specifically the reactive Web framework Shiny. This is usually a sure sign of a good match between learner and subject matter: an iterative process where learning and applying, tightly interleaved, form a feedback loop.