When comparing PyGObject / Python3 vs Tkinter, the Slant community recommends Tkinter for most people. In the question“What are the best Python GUI frameworks/toolkits?” Tkinter is ranked 3rd while PyGObject / Python3 is ranked 12th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Works particularly well on Linux, as many desktops use Python and GObject
GObject is a 'C' library with bindings to many other languages, so can be widely used.
Nice GTK.UIManager function to produce a menu system from a string.
Pro Free for commercial use
Pro Included in the standard Python library
You probably already have it, since it's included in the standard Python distributions.
Pro Easy to learn and get productive with
TkInter is a small library with a gentle learning curve compared to what’s out there. It has a straightforward API and is often the go-to choice for building quick GUIs for Python scripts.
Pro Building executables is less complicated
Compared to other GUI libraries, building executables for TkInter applications are simpler because TkInter is included in Python and has no other dependencies. This results in less complicated packaging requirements and smaller binary size.
Pro Fast
Cons
Con Doesn't work well if you're targetting Windows, even though there probably is a binding
Not very close to Windows look and feel.
Con No advanced widgets
TkInter does not come with advanced widgets out of the box (e.g. date picker).
Con Not good looking
You need a lot of code to make it look good.
Con No reliable UI builder available
There is no tool in the same league as Qt Designer (PyQt) for TkInter.