A poll done by JAXEnter to find out the which language is on your list for 2019 resulted in more surprise results like Dart is rising much faster than any language this time. Second language is Python and it is here for a strong reason because Machine Learning has gained and going to get more moummentum in comming years.
** Dart for Web and mobile application and Python for Machine learning is the best choice for 2019, You can learn dart to develop mobile apps using Flutter, Web apps but same time you can also learn Tensorflow(Written in Python) to make you mobile and web apps more smart**
Recently Google has launched the stable version of Mobile application framework Flutter to develop mobile apps for Android,iOS and Fushia(Google OS which will come soon in the Future)
Flutter is fast and better organized than its current competitors in the market like React Native, Ionic and Xamrin.
Flutter development is done in Dart 2.0 which is much better and stable then Dart 1.0.
If you good at Dart you can develop Mobile apps using Flutter. Web Application Frontend using Angular Dart as well or you can write fully fledged server application using Dart (Project HummingBird has done a remarkable Job)
Flutter is forked to develop system apps using Dart language which is going to be a strong competetor to Electron.JS in near future as well.
So I would recommnend you to learn Dart if you want to build something amazing.
As demand of smart application which can learn is on rise Python demand is also rising because every library related to Artifical Intelligence is written in Python. Tensorflow from Google is also written in Python which can be used to develop Machine learning model for web and using Tensorflow lite we can do the same for Android and iOS applications.
In scientifc research and in all most all kind of algorithmic calculation Python is used.
If you want to create Bot applications or recommend systems on web these can not be written without Python.
Pyhton frameworks like Django and Flask can be used for general web and API development. But if you feel you web app must have some smart features like Machine learning then you can integrate these feature easily if it is written using Django, Flask or in any Python Framework.