Linked the GitHub, but here's a post about why it was worth spending a few weeks compiling this list: <a href="https://sedimental.org/awesome_python_applications.html" rel="nofollow">https://sedimental.org/awesome_python_applications.html</a>
I like Mayavi, but I wouldn’t say it was a ‘great’ Python application; it’s a pain in the install for e.g. Something like NumPy or AstroPy are clearer successful scientific Python projects to my mind.