I have a project in mind and want to take on it and have chosen QT as the preferred framework to begin with. I have been trying to figure out how to start and have Qt package (SDK and Qt Creator) installed. The problem is - I am not able to figure out the exact use-cases of Qt Quick and Qt Widgets. I plan to make the project for a long-term purpose with these properties:
Considering that use-case, what would be a better choice - Qt Widgets or Qt Quick?
A little about me and why I chose Qt - I have been out of touch from C++ since almost 2 years and have not made anything serious in Qt but Qt is a preferable choice over Java (which I do not like much). Again, I lack experience with Python. In addition to that Python UI sucks and if I have to install QT framework for a good UI, why not make the entire thing in Qt anyway (considering I am okay with C++). So Qt is the preferable choice for me. Since the project would need to be cross-platform compatible, Qt is even more attractive to my eyes.
QML will provide more support for customising widgets in a simple manner, Widgets gives you a set of tools ready to go that gives you platform styled controls in a very simple way. Both have their upsides, both have their downsides, I'd personally recommend getting started with Widgets first as there's a lot more historical documentation for them, so if you need to research something you'll have a bigger base to work with.
From your comment above, there's been little development on Widgets as the Qt development team feel that they don't need any additional work at this stage. They're stable, solid and reliable, there's not much that needs to be done to be improved, and when people need custom widgets they end up creating them themselves.