[shynrou]

I'd recommend obsidian, works well on mobile and desktop, and documents are plain .md files in directories.

[seabrookmx]

+1.

I used to just keep a folder full of plain text files but recently (as in the last 2 weeks) moved to obsidian and the ability to add some simple markup (headings, code snippets) as well as search the content of the files easily has been a game changer.

Also it's just a thoughtfully designed, nice to use app (if you aren't an electron hater.. I daily drive VSCode, postman and Slack so am certainly not).

[PorterBHall]

Similarly, Joplin is great. Just migrated 10 years of note out of OneNote. Getting them out of OneNote was arduous; getting them into Joplin was a breeze.

[Kokouane]

+1

For syncing, you can either pay for Obsidian Sync ($10 per month, which is a bit pricy)

If you have a mac/iPhone combo, then iCloud sync is natively supported.

Other than that, Syncthing works well on Android/Windows/Mac, but I heard Syncthing on iOS is not that great.

[themadturk]

Obsidian Sync has been flawless for me (I got in on early bird pricing, so it's only half as painful).

Obsidian Git works well, and for getting stuff back and forth from a Git repo to iOS, Working Copy does the job.

[rmkrmk]

+ the Omnisearch plugin for a great search engine in Obsidian. It can index images and pdfs, too