The users loyal to zotero would appreciate very much that there is the option to mark the relevance of a paper and that these can be organized according to relevance. It could be done with a system with a qualitative classification system: nothing relevant / relevant / very relevant or + / +++, ++ / +++, +++ / +++ or 1/3, 2/3, 3 / 3 or another that you consider useful.
Thank you for Zotero.