I prefer paper notes (like these), but I’m often at my computer, so I most of my notes end up on my laptop.
I have a lot of notes in Org Mode format, but I’m trying to move them to Markdown files.
I like my computer notes to be in plain text so that the content is easy to manipulate with scripts — the notes can be versioned in Git, and standard text processing tools work on them: ripgrep, cat, sed, regular expressions, vim macros, etc. The text can be converted to PDF, LibreOffice/Word, or other formats with pandoc.
There’s also a poll over here with some comments: How do you like to take notes? [POLL]