PySimpleGUI takes less lines of code to build an application, but you do lose some creative aspect to it.

Tkinter would be better for large scale applications, but if you are just doing a short project, I would choose PySimpleGUI.

FYI: PySimpleGUI is built off Tkinter, so if you are looking for a specific feature, you might find it in their documentation: https://pysimplegui.readthedocs.io/en/latest/.