Joplin is an open-source note app that supports text, images, audio and PDF attachments. It earns fourth for keeping course notes and supporting material together, with rich-text and Markdown editing options.
It beats #5 because organised notes remain useful after a lesson ends, but #3 gives recall practice a clearer structure. Start with a consistent note title for each class. The desktop app is free; the optional Joplin Cloud service is paid. Decide whether you need that service before treating cloud storage as part of the free offer.
Source: Joplin · Cloud plans · AI illustration: Topnilo · OpenAI. Created with OpenAI; resized/recompressed.