When comparing GNOME Do vs Krunner, the Slant community recommends Krunner for most people. In the question“What are the best Linux app launchers?” Krunner is ranked 7th while GNOME Do is ranked 15th. The most important reason people chose Krunner is:
As it is written in Qt QtQuick using QML.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Plenty of plugins
By using the many available plugins Gnome Do can become a powerhouse of combined tools in one easily launchable and usable application.
Pro Themeable
Users can easily customize the looks of Gnome DO with the available themes in the settings of the app..

Pro Fast
As it is written in Qt QtQuick using QML.
Pro Opens folders/files also
Just by typing name of file or folder, it will give recommendations

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 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.
Cons
Con Has not been updated in a while
With the last update being dated Jan. 2014 development seems to be at a standstill.
Con There are few plugins/"runners", and some do not work as they are old
