first: OP is in HS or is just beginning college. Stated goal is to create analytics tools to track complex data. Application is at this point flexible. Machine learning fits best which is why I said it.
Second: addressing the difficulty of getting into a good CS PhD program (which I agree with) is a non-sequitur to the question of what OP should shoot for. Again, early in college. Of course no publications or research. That’s why college and working with CS profs.