Which.net library is a good option for manipulating (creating and editing) PDFs as at April 2020?

There are a multitude of such tools available, but it's all too easy to end up committing to development with a library which is old or buggy. So for clarity, I'm looking for a Library which:

 - Is stable
 - Has functionality for the classic things you'd want to do with a PDF (e.g. writing text, drawing lines, inserting images, etc.)
 - (preferred) has some kind of ongoing maintenance or development effort
 - (preferred) is free for commercial use