

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. Metadata extraction is also far superior with Zotero. 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. I think the only reason to use EndNote is if you want to be able to heavily customize reference types. Including the new version of EndNote truns a bit better and has a more modern UI.
