When comparing Zim vs Org mode for Emacs, the Slant community recommends Org mode for Emacs for most people. In the question“What are the best personal Knowledge Base apps?” Org mode for Emacs is ranked 1st while Zim is ranked 4th.
Ranked in these QuestionsQuestion Ranking
Pro Allows for organized, wiki-style navigation
Notes can contain links to other notes, allowing you to reference important information when needed. This way the user can connect and reference many different pages in the app, keeping things clean and structured, unlike Evernote, which makes this a good Evernote alternative.
Pro Plain text data format rather than proprietary
If/when the app is no longer developed (or if the user simply decides to no longer use the application or view/edit it on a non-supported platform), this can still be done with any plain-text editor.
Pro Automatically manages files and folders
Zim will automatically create a folder structure that fits your page hierarchy and adds/removes files such as images to/from appropriate folders.
Pro Good export options
Zim supports HTML, LaTeX, Pandoc Markdown, and RST. This allows ones documents to be easily used in a wide selection of other apps.
Pro Support for multiple platforms
Windows, Linux, and BSD are supported with their own clients. This is nice for those that use multiple operating systems but still want to use the same app on each.
Pro Libre/open source
Pro Cross platform
Emacs runs on all platforms, Windows, Linux, OSX, even Android and IOS
Pro Exports data to PDF, LaTeX, HMTL and other
You can even build presentation or blog from your data
Pro Can be as simple or as complex as you want
Org mode started out as a simple outlining/note taking app. Then each outline heading can optionally be a TODO list item. And if you desire, you can add SCHEDULE and DEADLINE dates. (Schedule being the date you'd like to start the item.) You can customize the TODO states to add things like DELEGATED, WAITING, BLOCKED, etc.
Pro Supports tables with formules (quite powerful!)
Pro Inline image displaying
Pro Plain text data storage
Pro Uses Emacs
Pro Free but copyrighted
Con No native sync support
Zim notes don't automatically synchronize with other devices or offer built-in cloud sync support. Of course the user can add the files to Dropbox, or something similar, to then open them on another device with the app installed. But this is more of a work-around than a built-in solution.
Con No mobile app support
This is a desktop app and there are no mobile versions available. This can make it more difficult to use on-the-go if using cloud storage to store files from the app, as there is no mobile app version to access those files.
Con Looks ancient
Zim has a very plain and outdated interface.
Con Obtuse documentation
The documentation assumes a level of understanding of basic Emacs usage that not all users may have.