When comparing Otter Browser vs Falkon, the Slant community recommends Falkon for most people. In the question“What are the best desktop web browsers?” Falkon is ranked 4th while Otter Browser is ranked 7th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Under GNU GPL
A better license for a browser than a restrictive "all rights reserved".
Pro Open source
Anyone can contribute to the Otter Browser, solve common issues, bugs.
Pro Legacy Opera
Aims to recreate the best aspects of Opera 12.x.
Pro Developed by KDE
Pro Lightweight
Pro Free and Open Source
GPLv3 license.
Cons
Con External Rendering Engine
It uses the Qt Web Engine from your local Qt installation which is usually not often updated.
Con No support for addons
Con Under GNU GPL
It is licensed under GPL which is less permissive than other opensource licenses like BSD or MIT.
Con Weak multimedia support
It has some issues with multimedia content eg. Non-playing videos on webpages.
Con Now under the KDE umbrella
Qupzilla is now discontinued and renamed to Falkon. It will also now be a part of KDE and will probably need more dependencies like kde-frameworks in the future.
Con Linux-only
Con Bookmark management not the strongest part
It often requires quite a lot of clicks to add and remove bookmarks.