Adding proper metadata to releases. Why are we still trying to decipher release titles, why not add a little metadata JSON file to every release and make the info available to the search API?
Also keeping multiple different versions of a release in Arr apps, like ebook and audiobook in different languages. Right now I'd need 4 Readarr instances to get the English and German audiobook and ebook versions of a book, and don't even think about letting them manage the same root folder!