What is the de facto library for creating Python Daemons
I went with Sander Marechal's A simple unix/linux daemon in Python, it is simple, and you work with it by creating a subclass and overriding the run() method, which feels a very natural way to do things (rather than the with context: approach of the python-daemon module.
Twisted comes with twistd.
http://twistedmatrix.com/documents/current/core/howto/basics.html
You can wrap your application as a plugin for twistd.
For making a daemon program that will work correctly with the various runners in operating systems (e.g. init, systemd, launchd), the python-daemon library is the de facto way to write just the daemon part and let the operating system do the rest of the job correctly.