When comparing Gitit vs Wiki.js, the Slant community recommends Gitit for most people. In the question“What are the best multi-user wikis?” Gitit is ranked 4th while Wiki.js is ranked 6th. The most important reason people chose Gitit is:
Giti has a multitude of formats that it allows to be exported, including LaTeX, ConTeXt, DocBook, RTF, OpenOffice ODT, and MediaWiki markup.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lots of export formats
Giti has a multitude of formats that it allows to be exported, including LaTeX, ConTeXt, DocBook, RTF, OpenOffice ODT, and MediaWiki markup.
Pro Supports markdown
Getit supports markdown, a plain text formatting syntax that is designed so that it can be read by HTML.
Pro Free and open source software (FOSS)
Licensed under GPLv2 so you can download source code and customize to meet your needs, provided that you know or are willing to learn Haskell.

Pro Can be used collaboratively by multiple people

Pro Renders math
Using MathJax.
Pro Modern UI
Modern and elegant UI.
Pro Search engine
Built in search engine.
Pro Built in access control
Restrict access to your Wiki to certain users or even just parts of your content.
Cons
Con Requires Haskell
On some Linux platforms a binary package for Haskell may not be included in the standard repositories. So, it will be necessary to compile Haskell from source code or find a non-standard package repository, which may seem like a hassle if you don't use Haskell for anything else.
Con Full of UI bugs and missing features
Many bugs that detract from the user experience.
