Stuck with a handful of options, students often ask which framework or discipline (e.g. video games, full stack web development, etc) should they specialize in? Here’s one way to sort through the question.
Can you learn it? Are there materials or a school that can get you there from your current level? If on quick glance you don’t see a path, then abort.
Is the technology booming or dying? If you had to choose between two technologies, choose the ascending one. Use Stackoverflow trends to compare the activity on the technologies.
What are your salary requirements? Check Glassdoor for the average salary in your location. If you aren't happy with the salary of a specialty, ditch it!
How many jobs are there? Check Indeed (or any other job board) for how many jobs are listed in your area. The more jobs, the easier it'll be to get a job.