When comparing MSYS2 vs just-install, the Slant community recommends MSYS2 for most people. In the question“What are the best Windows package managers?” MSYS2 is ranked 5th while just-install is ranked 13th. The most important reason people chose MSYS2 is:
Easily install most linux command line tools.
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Pros
Pro Easy Install
Easily install most linux command line tools.
Pro Open source, free and libre
Pro Works within Windows guidelines
The programs are listed in Control Panel and can be uninstalled using standard Windows procedure. Downloads from original source, doesn't repackage. It just automates the install process, skipping prompts and dialogs.
Pro Can install bundles, without needing command line parameters
Like Ninite, you can create a custom .exe installer which automatically downloads and installs a package selection -- no command line switches needed. https://just-install.it/customizer.html
Cons
Con Limited package selection
Since project is open source there is way to add new packages, but you'll have to figure out how to configure new package and submit pull request. There's no army of volunteers responding to requests.