When comparing Krunner vs DockbarX, the Slant community recommends Krunner for most people. In the question“What are the best app launchers for UNIX-like systems?” Krunner is ranked 8th while DockbarX is ranked 10th. The most important reason people chose Krunner is:
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Specs
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Pros
Pro Opens folders/files also
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Pro Extensible with plugins
Krunner can be extended with the use of "runners" which are essentially plugins for the app launcher to allow for extra functions.
Pro Fast
As it is written in Qt QtQuick using QML.
Pro Lots of handy features
Such as a fully featured calculator, file opening, browser functions, currency conversion, date/time functions, etc.
Pro Great integration with Plasma, developed by KDE
Pro Can be used to open websites
By just typing an URL into the text box users can have the site open in their default launcher.
Pro I'm able to find open tabs from browsers with KRunner which is very nice
Even supports edge browser.
Pro Easily customized
DockbarX has inbuilt settings that allow the user to easily customize the look of the dock, from changing the text color to the background color.
Pro Great plugin to help blend in to XFCE4 panel
DockbarX has an available plugin called "DockBarX Xfce4 Panel plugin" that allows DockbarX to blend in seamlessly with the XFCE4 panel, which is great for XFCE users due to the limited options of the default panel.
Pro Easily the best Win 7 taskbar functionality
If you want a combined launcher/manager, a la Win 7, this is it.
Cons
Con There are few plugins/"runners", and some do not work as they are old
Con Not actively updated
Less than a dozen updates since 2014: https://github.com/M7S/dockbarx/commits/master