I have used both extensively. Including the new version of EndNote truns a bit better and has a more modern UI.

I think the only reason to use EndNote is if you want to be able to heavily customize reference types. If you are fine with the Zotero provided reference types or the work-arounds for things like treaties (that do not have a reference type), Zotero is more stable, cheaper, easier to use, and has several quality-of-life features absent in EndNote, such as the ability to extract highlights from PDF with Zotfile and save web snapshots. Metadata extraction is also far superior with Zotero.

If you really need to be able to customize reference types and you are on a Mac, Bookends is super customizable but not quite as polished as Zotero and has zero sharing features.

I use Bookends for personal writing (I work with obscure legal and international jurisdictions that do not work well with Zotero) and Zotero for teaching and some co-authoring (and just hand write legal citations) and this works fine. I have an EndNote license but I don't think I have used it for years.

Very helpful. I worry about customizations. I have my own customized Templates (in Output Styles) in EN—for instance, a format for Translated and Edited by; one for journal articles as editions; one for chapters in authors own collection; one for book chapters; one for ancient texts (edited by one person, translated by another). I also have several customized Output Styles for American and European presses. I'm finicky about how many authors' or editors' names are given before an "et al." is used (easily set in EN); use of initials or entire first names; sort orders; commas with ", and" for x names of authors/editors or just "and" for 2 such names; etc.

I haven't looked far, but Zotero seems customizable if you want to play with a lower level of coding. That can be exhausting, I imagine, or tedious. (Not that getting it all right with EN isn't tedious at times; easier now than in the past.)

I think describing CSL as low-level coding is fair, even with the visual editor.
I'd agree that there's a limit on how far you can take Zotero item types -- some of the examples above, such as chapter in an authors own collection, just won't work well.

EndNote styles are easier to customize. However, you should ask yourself how important it is to have your own complex custom styles. Although not as straightforward as EN it is nonetheless almost trivial to edit one of the thousands of Zotero styles to meet your needs for "... how many authors' or editors' names are given before an "et al." is used (easily set in EN); use of initials or entire first names" ... etc. "Edited by one person, translated by another" is easily handled with Zotero.

The greatest benefits I see with Zotero over EN are 1) If a publisher or database changes its structure it can take weeks or more for EN to fix its translators that import records from the website while with Zotero the problem is usually fixed within hours; 2) Bugs [or updates needed to adjust for changes made to various word processing software], too, are often fixed within hours of reporting; and 3) Technical support (for very basic or quite complex issues) is available here directly from Zotero's developers [and often from the lead developer] or from very experienced volunteers (24 / 7) sometimes within minutes of the request and, unlike EN's web support, you will never receive snarky unhelpful replies.

I'm somewhat biased by my experience with EN. In the midst of writing my doctoral theses in 2007 I switched from EN to Zotero because of EN bugs that slowed me down. Many colleagues and students have transitioned from EN to Zotero and I've only heard comments of pleasure about the switch. I still help students who use my university's license to free EN and some of what was mentioned (chapter in an authors own collection) isn't so easy with EN either.

Emiliano is one of those very-helpful always polite volunteers who is the developer of the essential plug-in, Better BibTeX.

This is all extremely helpful. I am between book projects, so now is a good time to give Zotero a try.

If I do, you will probably hear from me in the future. Snarky replies are more than welcome.

Thanks, All

The "smart group" function is the hit point. Zotero now can not assembly searched results into subcollections.

Endnote maybe automatically visually nest smart groups? I could see how that would be useful.

I was using EN (sooooo slooooow) for many months, later Bookends (excellent, but Mac only) for several years and now Zotero since 2018. Zotero is very good, but still with some quirks e.g. poor preview of abstracts (in EN and Bookends one may create a style for previewing these, with larger fonts for the abstract) and difficult creation of new styles. What I miss most is the ability to update records metadata automatically. Apart from these limitation Zotero is a fantastic product, particularly in terms of speed and stability.

I used ProCite from 2000 to 2006-ish, then switched to EndNote, which I used until mid last year, and have been massaging the import of my EN references into Zotero for a while now.

For me, it is largely the FOSS nature that has drawn me to Zotero (and that it runs on Linux). I also have it paired with Zettlr to do note-taking - the inter-operability is quite good.

This isn’t really the best place to ask about Endnote functionality