When comparing Kobo app vs Sumatra PDF, the Slant community recommends Sumatra PDF for most people. In the question“What is the best Windows eBook reader?” Sumatra PDF is ranked 2nd while Kobo app is ranked 3rd.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Sync eBooks and position
The Kobo app will sync the users whole library as well as each position read for each title. This way a user can pick up where they left off from one device to the next.
Pro App supports a multitude of operating systems
The Kobo app supports just about every main OS out there. iOS, Android, Windows 8, Windows 8 Phone and Blackberry 10. By being available on so many platforms the user is able to read their eBooks on any device they wish.
Pro Starts quickly
Pro Free and open source
Sumatra is available for free, licensed under GPL with source code available on GitHub.
Pro Low resource usage
Pro Does not have heavy editor features
Annotations and other heavy features are just not needed in reader.
Pro Extensive keyboard shortcuts
Pro Elegant interface
Pro Portable
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 Multilingual
It's available in 69 languages.
Cons
Con No way to add own titles
The users Kobo account has no way to add outside titles to the users collection.
Con Windows only
Con Lacking in features
Sumatra aims for simplicity at the expense of functionality. For example, there's no way to annotate PDFs or edit them.
Con Fonts are not smooth enough
Not as smooth as e.g. Adobe Reader. No anti-aliasing
Con Cannot crop empty fields
Just got used to this killing feature on Goodreader on Mac.