Support of Linux, Windows, BSDs, and Mac OS X makes pygame a great option for any user. Installation can be done via package manager on Linux and by binary installers for OS X and Windows.
The docs are messy, and some basic functions are infuriating to work out. There's even some places in the documentation where it's clearly wrong about how a method is called/what the arguments really do.
A small advantage, but being a core Python developer, it may be the best to stick to the roots and develop with pyglet as it is able to compile using other Python interpreters.
With a plethora of documentation on the core Cairo library and the bindings for Python, users will be able to turn to the documentation, API, or translate examples from other languages to work with PyCairo.