In my dream a note taking app has this...
Here's my current view (and it will change over time) ranked ordered from high to low in response to @CatoMinor3's question on Twitter:
"What makes a modern note-taking / #PKM app?"
1. My data, all mine!
2. Open Source Software
3. Encrypted at rest
4. Encrypted backup
5. Labels / tags
6. Deep linking
7. APIs
8. Inline images
9. Sync
10. Inline checklists
11. Markdown
12. Highlight
13. Export to PDF
14. Export to image
15. Markup
16. Extensions
17. WebDAV
18. Tables
19. Outlining
20. Inline audio recording