I use Notability on iPad for the majority of my notes. It's free now, organising features are extensive enough for my use case and it auto-backups to Google Drive as PDF. GoodNotes is an alternative.
Other than that, I use Notes on iOS sort of as a "slip box" and Notion for more tabular/structured data (though beware of privacy concerns with Notion).
People doing work in or tangentially connected to EA often have a lot of tasks on their plate. From organizing events/clubs to being a student or autodidact, to working on a series of often complex projects, there is a lot of work to be done. Given the plurality of tasks at hand and different forms of learning, I doubt there will be a one size fits all note system - especially when we consider how individual of a process note-taking often is. But I still feel like it would be really useful to share what systems people use down below.
I am a current undergraduate student and Cornell EA president, along with running my own X-Risk Communication company. There's a lot of learning to keep track of and I would love any recommendations from the EA community on existing systems they use for note-taking, idea generation/exploration, writing, and recall.
The current state of my note-taking system is a mix of Evernote, google docs, PDF annotation tools, and obsidian for building a slip box but if anyone has a more delineated process for learning --> note taking --> ease of use/application in projects I'd love to hear it down below! Emphasis on PDF annotation integration!
I think a lot of people have spent time on this. I currently use Obsidian for longer-form note taking and building up more complex thoughts, but mainly I just use backlinks; the Roam-style graph view is hip but I don't find it particularly useful. Then I use apple notes for on-the-fly, unimportant jots that I may or may not get ingested by Obsidian in a more structured form when I'm on my computer. I manage all of my productivity and to-do lists on one Apple note and my Apple calendar. Longer-form works of writing that have taken something of a single cohesive shape get their own Google docs. Finally, I manage all my sources on Zotero, with a few folders for broad subject areas and one big messy folder where I dump forum and blog posts I've read or skimmed that I might want to find later. I also read and annotate all PDFs within Zotero.
I'm pretty happy with this system currently, although I wish I had a good, easy-to-set up Zotero-Obsidian integration, and that it was easier to copy-paste links between Markdown and plain text editors. If anyone has suggestions on either of these that'd be great.
In general, I think it's a well-explored space and imo nobody has come up with anything that's convincingly a large productivity multiplier; for me, it doesn't seem like a promising place too put too much thought into at the moment. This comment thread on LessWrong raises some more interesting points.