I use Joplin every day for work, and review notes on the commute home from phone. Love being able to write in Markdown, fully encrypted across all devices, full hierarchical structure plus tags support. The UI is "basic", but so are my needs. And if it goes away, I have an up-to-the-minute backup organized by those same folders and markdown files. Several new releases since I started using it 6 months ago.

The lack of tags support on mobile and the proprietary storage format is what drove me away from OneNote.