Obsidian_notes
It’s gotten to the point where I couldn’t manage without Obsidian. I keep everything I learn there.. tag it; place in dirs, subdirs; link and cross-link.
I use Folder Notes, Auto Note Mover, Reminder, Text Snippets and Bases a lot (sometimes Dataview).
(also: Execute Code, Multiple Column Markdown)
One thing I don’t use much - but should - is templates. When I create that habit, it will probably be even better.