Recommendation can sometimes be hard without knowing the direction you want to focus on right now and also in your career. If you are not sure, like others have said Python, Javascript and web apps are a big hires right now. Another person also suggested Pandas which is great if you are looking more at big data and analytics. It can also be hard because "good" solutions might take more effort than you are planning to put into this.
Some suggestions
Python, D3, and Flask (maybe with bootstramp for UI) might be good if you are looking towards web and backend.
Python, Pyside or Tkinter would be good for desktop
Python Pandas for data analysis and big data focus.
I do not think any suggestions have been bad, just depends on what you want to focus on and how you want the interactions to feel like. Maybe making hypothetical assumptions on who the user of this data is, which would push you in a certain direction. Is this a lonely engineer trying to quickly dig through data, maybe a desktop app would be better. Or is this a general person with minimal knowledge, a well design web app with good workflow might be better.