Ranked in these QuestionsQuestion Ranking
Pros
Pro Supported by the Qt Company
Qt for Python aka PySide2 is the official set of Python bindings supported by the Qt Company.
Pro Qt widgets
Possibility to use a traditional widget-based user interface.
Pro QtQuick/QML
Possibility to use a declarative approach to define the user interface.
Pro Weak copyleft
PySide is licensed under the LGPL, which makes it easier to incorporate into commercial projects than PyQt.
Cons
Con Similar to PyQt, you need a C++ background. at least you can read C++ code
Qt's document is poor, and Qt for Python(PySdie) is even worse. this document assumes that you are already familiar with Qt. if you want to customize a Widget, you need to look at the Qt C++ source code to know what to do.