I’m a Zotero user, but interested in Jabref because of some of advanced features.
I create a lot of entries for old texts, without isbn or doi. I have to do it manually, and speed and convenience are of primary importance.
Correct me if I’m wrong, but in Jabref I have to create new entries one by one. The process is slow, important fields (like pages or place of publication) are in the second tab, so I have to use the mouse.
When it comes to quickness, nothing can beat Excel. I guess that editing entries directly in the table is not planned in the future? Zotero can’t do it either, but manual creation of entries is faster, because all fields are in one tab (no need to use the mouse) and you can batch edit several entries at once.