I’m on the complete opposite of the spectrum. Keeping files in a file system (folder structure), notes in a note system and email in an email system makes things a lot easier for me to manage.

I only store text, with some minimal formatting, in Evernote. Lately I’ve been relying on Google Docs a lot more for collaborative writing, which I previously did in Evernote; sync is so unreliable, I have given up. Real time editing within Google Docs is so much more efficient.

It seems like iCloud Drive with tags might do the trick for you. You could sync files across multiple devices, make use of a mix of folders and tags for organising the content and you could search within the content of documents too.