Nothing has come close to Microsoft's One Note for me when it comes to note taking apps.
The combination of One Note and an iPad with the pencil is particularly powerful.
Actually, tagging is one of the things OneNote should do better.
It doesn't support hashtags out of the box so tagging means selecting from a list of predefined tags.
One of the things that really annoys me about OneNote (I'm a big fan of it though.)
It always felt odd that the same app that reliably converted my handwriting to text a decade ago had a small, fixed number of tag slots and no ability to import icons. I remember thinking "well surely this was a v1, they'll improve it in later versions" but no, not even the tiniest change.
- internal links doesn't work on mobile.
- local shared folder mode doesn't work in later versions. This was brilliant for places that has restrictions on what they can upload to the cloud. OneNote could often replace internal wikis for smaller companies (in some areas it was even better) but now that becomes less viable as OneNote for desktop gets older.
It does support custom tags. I don't think there's a way to add custom icons, but custom tags are definitely a thing.