I love #LibreOffice (in particular Writer) because it makes it fast and easy to lay out the internal files for paperbacks I publish through POD platforms. It is more powerful than Web-based tools, has better layout features than MS Word, and it's free -- what's not to love?
I also use Calc for tracking my writing productivity. As a writer who has not yet had commercial success with his books, free tools like this mean a lot to me.
				
				