New and Improved Notes
With Notes on macOS Catalina, you get a more powerful app. If you use this as your depository for everything, you'll appreciate this upgrade.
You can find notes faster with a gallery view. You can share a folder of notes instead of just sharing note after note. These two features are a major reason to install macOS Catalina, but you get more.
One other killer feature is auto-sorting the checklist in a note. When you check off an item as done, you can have Notes automatically move it to the bottom of the list. It's very satisfying when you finish something.