When comparing Code::Blocks vs Qt Creator, the Slant community recommends Qt Creator for most people. In the question“What are the best IDEs for C++ on Mac OS X?” Qt Creator is ranked 7th while Code::Blocks is ranked 9th. The most important reason people chose Qt Creator is:
Qt Creator has a code model which basically has the same information as the compiler. So it can do really nice syntax highlighting (e.g. of virtual methods or local variables) as well as provide great code completion.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free/Libre/Open Source
Pro Cross platform
Code::Blocks is available for both Windows and Linux, allowing you to use the same IDE across both OSes if you use different machines.
Pro Easy to use
Easy to pick up, for example much easier to include libraries.
Pro Debugger multi-threading support
The debugger supports multi-threaded processes for faster debugging.
Pro Lets you choose the compiler
Code:Blocks lets the developer choose which compiler to use, giving you a higher level of control for on your development workflow.
Pro Great syntax highlighting and auto-completion
Qt Creator has a code model which basically has the same information as the compiler. So it can do really nice syntax highlighting (e.g. of virtual methods or local variables) as well as provide great code completion.
Pro Integrates well with non-IDE workflows
Qt Creator uses normal .pro-files, CMakeLists.txt, Makefiles.am, etc. for its projects and rarely needs special configuration for projects.
Projects can be built on the command line as usual.
Pro Built-in Qt GUI editor
Allows for the creation of a window based UI in a graphical editor, no code required to build the UI.
Pro Fast and fully keyboard-navigatable
Responsive UI, no need to use the mouse for the power users.
Pro Supports CMake
Pro Very responsive when compared to similar software
Pro Much space dedicated to the code
Small and beautiful UI, almost all the space is dedicated to the text with hardly and toolbars. Can actually be used on a 1024x768 pixel screen.
Cons
Con It's hard to make the code readable
Due to the problems with indention, it's hard to make the code look nice.
Con Poor code completion
The code completion for Code::Blocks is rather poor compared to other IDEs
Con Poor refactoring
QtCreator has lack of refactoring features. It's not even close to Resharper++ or CLion.

Con Poor multi-window mode support
While multiple windows are supported, many operations will activate in the primary window (debug, goto-line... etc).

Con Qt-focused
Qt Creator is focused on being an IDE for Qt, as a general purpose IDE it performs quite well, but there are areas which are lacking such as project file support (support for generic/CMake projects lags behind Qt projects).
