Key features:
- PDF annotation
- S-pen/stylus support
- Sync (preferably NOT just via Nextcloud…looking at you, Saber)
- Handwriting recognition is a plus, but not required
As mention above, Saber fits the criteria well, but I don’t use Nextcloud and that is the only sync available in that app (unless something has changed in the last couple of weeks). I have a Galaxy phone and tablet that both support S-pen and Samsung Notes is excellent, and free, but they’re not exactly privacy concious, so I’m looking elsewhere. I had considered the Excalidraw plugin for Obsidian, but I’m not sure if that works on the Android version of the app.
I should mention it’s not a free app. But it has the best handwriting recognition I’ve ever seen. I write worse than a toddler and it still converts without fail to the correct text. If I can sync without using Dropbox and Drive, I’d be fine using it as Samsung Notes alternative