I really like more_itertools when I have the chance to use it, it's really nice and comes with lots of handy little things.
One of my favorites is the Rich library, making it simple to develop nice-looking CLIs.
Favorite from the Python builtins is Pathlib and the caching abilities of functools.
Any data analysis project starts out with pandas and jupyter.
I really like more_itertools when I have the chance to use it, it's really nice and comes with lots of handy little things.