When comparing Zim vs Joplin, the Slant community recommends Joplin for most people. In the question“What is the best cross-platform note-taking app?” Joplin is ranked 2nd while Zim is ranked 8th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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 Offline access
Pro Open source
Peace of mind that there is no malicious piece of software in the app.
Pro Encryption
Pro Cross-platform
Supports Windows, Mac, Linux, Android and iOS.
Pro Supports file attachments
Pro Supports markdown
Pro Supports tags for notes
Pro Web Clipper
Browser extension saves full pages, clean content, or screen selections to new notes.
Pro Optional CLI interface
Provides a CLI interface for terminal lovers.

Pro Supports multiple languages
English, French, and Spanish, Italian, German, Czech and many others.
Pro Active user forum with support from app creators
Support, troubleshooting, and new feature requests are easy to make at the user forum and you can contact the app creator directly.
Pro Dropbox support
Can sync using Dropbox.
Pro Nextcloud support
Pro Timed alarm reminder for to-do lists
Cons
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 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 Looks ancient
Zim has a very plain and outdated interface.
Con Sync issue under Linux
The Linux client has a bug that requires the user to click the mouse frequently in order for sync to proceed. This bug has been open for a while.
Con Gargantuan memory footprint
1GB+ of memory for taking notes.
Con Old school interface
Con Bloated
This project is suffering from feature creep and uses a lot of memory for a note-taking app.
Con App Image launches very slowly
On Linux, you can only install via App Image, which take 5+ seconds to launch. I can launch LibreOffice in under two seconds.
Con Sync issues on Windows
No way to change account settings and sync easily corrupted.
Con Weak tag searching
Joplin can currently only search for a single tag at a time. None of the boolean operators (AND, OR, NOT) are available for use in searches. This greatly diminishes the usefulness of tags in Joplin.
Con Can't create tags from the mobile app
