Depends on what you do and what you use. I like Zotero because it integrates perfectly with LibreOffice and with ResearchRabbit – the latter is an amazing AI web application that allows you to build up a picture of the literature related to the papers you already have. ResearchRabbit synchs with Zotero, so new references are added to your library. Zotero is also fast and accurate at finding the metadata on a pdf you drop into it.
I guess, too, that "best" also can mean "best value". I think that Zotero has evolved to the point where I'm not prepared to pay money for Endnote.
And I have to say that the EndNote user interface has evolved from being the ugliest and most unintuitive software of the 1980s to the ugliest and most unintuitive software of the 2020s.
Ronán Michael Conroy has summed up the debate, I really start hating the recent changes in EndNote. It is really annoying.
I have used Zotero, it had a slight unintuitive interface, but with some practice, its worthwhile. and I hope Zotero has introduced reference customization for each journals (though they offer prebuilt libraries/format).
I find Zotero as most useful compared to others (Endnote) where you have to manually input information. Zotero only needs DOI, PMID, etc and all information will be pulled in.