When comparing Sumatra vs Calibre, the Slant community recommends Calibre for most people. In the question“What are the best desktop readers?” Calibre is ranked 1st while Sumatra is ranked 2nd.
Ranked in these QuestionsQuestion Ranking
Pro Book updates on the fly
If Book font, style is changed, Sumatra will take the update instantly, No need to close first and import again! Huge time saver for self publishing.
Pro Reads many file types
Including PDF, XPS, DjVu, CHM, EPUB, Mobi, FictionBook, PalmDoc, and comic books.
Pro Free and open source
Sumatra is available for free, licensed under GPL with source code available on GitHub.
It's available in 69 languages.
The application consists of a single file that can be run without installation. You can put it on an external device, such as an usb thumb stick and run it on any Windows machine from the thumb stick.
Pro Open Source
Calibre is available for Linux, OS X, and Windows, 32-bit or 64-bit.
Calibre has an optional portable build that can be stored on external media along with the users library. It can then be opened from the external media on any windows device.
Pro Powerful book management software, very customizable and scriptable
Features include metadata editing and downloading, coverpage downloading., book tagging and categorization, webpage-to-ebook converter for popular websites, etc. Lots of plugins available to extend functionality.
Con Windows only
No Linux or OSX versions available.
Con Average, non-power users might find the interface somewhat daunting
The interface, while functional is not the most attractive or intuitive which may put some people off and discourage their use.