Article/Document writing and management

I've recently become involved in a job that requires a lot of article writing, mostly scientific, with rich text, pictures and sometimes math text. I'm a huge fan of tags, as I find them essential for sorting and filtering by keywords, thus avoiding the clutter of infinitely nested folders.

So, in short, my question is: what app or entire workflow (for OS X) do you suggest for writing such articles and managing them with folders, "collections", "groups", "notebooks" or whatever they are called, and tags?

If there is a lot of math text, I mainly write with Texpad, a LaTeX editor. If there are rare equations, I use Archimedes, a MultiMarkdown editor. But none of them comes with management features and the Finder tags are too few and restrictive.

Also, ideally, I should have a similar workflow with similar results on iOS, since I carry my iPad with me a lot and I'd like to read, edit and manage those articles on it too...

I've been searching crazily and I really couldn't find anything satisfactory. The best finding was Together app, but it lacks Dropbox support, a huge drawback for me, since iCloud Drive, the only cloud that it supports, is far from Dropbox's capabilities.

Thank you very much for your time and please excuse me if I wrote in the wrong place, I'm new here (although not new in the StackExchange world).

And Happy New Year to everyone! :)