When comparing Cairo-Dock vs Polybar, the Slant community recommends Polybar for most people. In the question“What is the best panel/dock for Linux?” Polybar is ranked 2nd while Cairo-Dock is ranked 7th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Easy to tweak and make your own themes
Drag and drop, change icons, use effects, etc. It's fun to play with. It's not a basic dock program and the GUI is good.
Pro Cairo-Dock session
Users can choose to launch a stand alone Cairo-Dock session where the dock also serves as a taskbar where all apps are launchable such as in any other DE session. There is a composited version and one without.
Pro Popular and usually found and installed from a distros repo
Due to the popularity and how long Cairo-Dock has been around it is more often than not found in a distros repos, which is very convenient to get the app installed.
Pro Easily themed
Cairo-Dock has built in settings to install and use themes for the dock and icons. Definitely more robust in this are than most other docks available for Linux.
Pro Feature rich
Pro Good design
It has a good example design which makes it really good.
Pro Eye candy themes
Pro Configuring doesn't need to be hard
Many configs can be found on the internet,
Cons
Con No updates since 2016
Certainly no PPAs for modern releases of Ubuntu.
Con Poor/No system theme or icon integration
Docks use their own theme, own theme colors, icons, layout's and theme engines.
Con Hard/Underwhelming to configure
Cairo dock proposes a feature rich tool, tweakable to any degree. The configuration menus are at times inappropriate, shallow and uninteresting, complex to navigate, and prefab-centric. Rarely offering a satisfying preset, and always unsatisfying to tweak.
Con Can be heavy on resources for weaker systems
Cairo-Dock is more on the heavy side when compared to other docks, which is something to keep in mind for those that are on low resource systems.
Con Configuring can take time
Configuring polybar can be time consuming.
Con Weird to configure
Hiding the Unicode symbols is tricky.