When comparing Zazu vs Synapse, the Slant community recommends Synapse for most people. In the question“What are the best app launchers for UNIX-like systems?” Synapse is ranked 9th while Zazu is ranked 28th. The most important reason people chose Synapse is:
Synapse is pretty rock solid. Works as expected and launches applications fast.
Ranked in these QuestionsQuestion Ranking
Pros
Pro It looks pretty
Pro Extensible
List of plugins: http://zazuapp.org/plugins/
Pro Free & open source
Pro File system search
Pro Look/feel like macOS's Spotlight
Pro Clipboard history
Pro Rock solid
Synapse is pretty rock solid. Works as expected and launches applications fast.
Pro Can run commands just as a terminal would
Users can run commands such as sudo apt-get update
from within Synapse, making for a convenient way to open or run items/commands.
Pro Zeitgeist powered
Synapse searches the Zeitgeist log, which tends to be a pretty quick way to do searches over other app launchers.
Pro Includes a Zeal plugin
Includes a Zeal plugin to make searching faster.
Cons
Con Finicky json config file without decent documentation on the process.
Con Tiny library of plugins
Con Inactive development
Con Synapse is an abandoned project
The latest release was 7 years ago and the Launchpad page is a ghost town
Con Unable to search whole system
Due to Zeitgeist being used the search is not as robust as if it were using Tracker. Of course using Tracker has its own downside like battery drain, so currently there is no "best" solution.
Con Bound to control+space
Due to this it interferes with common IDE layouts for recommendations. Modifying hotkeys file doesn't adjust this.