Org-ref is not a bibliorgaphy manager I would say. It just extends Org and BibTeX modes with some (a lot of actually) custom functionality and sort of connects the two.
I use Org mode to write documents that are then exported to LaTeX. I, however, don’t like too much literal TeX in my Org documents, so for me Org Ref provides a convenient way to have a non-LaTeX-style markup in Org. And it is also very convenient to open PDFs and URLs from the
cite: style links, which I am used just to type manually, by the way.
Since Org Ref uses BibTeX as the bibliography management backend, you would inevitably end up editing BibTeX files by hand. Org ref provides some custom functions to streamline this as well as to fetch BibTeX from DOI and even PDF files but, similar to Jethro, I found they do not suite my needs and I couldn’t find a quick way to tweak their behaviour.
I personally use BibDesk (MacOS only) to manage bibliography. It also uses BibTeX as the database format, so integration with Emacs tools that use BibTeX is pretty straightforward - they are all just different interfaces to interact with the same
Switching from Zotero to BibDesk was a conscious choice because I wanted to have a single database that I can work with using different tools. Exporting from Zotero to BibTeX, and most importantly, re-importing it was too much hassle for me back then.
Windows and Linux users seem to have only one full-featured option that uses BibTeX as the native database backend - JabRef. It’s rock solid and can do many things, basically everything one needs, but I can’t force myself to use any Java GUI.
There is also Ebib - a powerful native Emacs BibTeX manager. I’m currently exploring its functionality and when I find a way to replace its own note management with Org Roam, I will probably switch to it.
Rephrasing what Nobiot said, if you need something more complex than just retrieving the BibTeX metadata and the associated PDF files on a desktop computer, then you probably need to stick to Zotero.
My workflow — 1. copy a DOI, 2. paste it into BibDesk, 3. run “retrieve BibTeX from DOI”, 4. copy the BibTeX key, 5. download PDF, 6. rename PDF with the citekey, 7. update the database — may seem too tedious compared with the fully automatic Zotero style, where you have a magic button that captures the page, retrieves everything, files the PDF and exports to BibTeX. I, however, have a full control of each step and enough time to reflect on what I’m doing.