I've been using GCC & friends for a few years now, building mostly for the Cortex-M23. GDB has been a godsend, with a J-Link you basically have as much runtime

I've been using GCC & friends for a few years now, building mostly for the Cortex-M23. GDB has been a godsend, with a J-Link you basically have as much runtime debugging support as you would on a hosted system. This is especially helpful in cases where logging would slow down the operation of the system too much. We're also very successfully using CMake as our build system, as opposed to Make itself. It lets you organise your build system & support different configurations & dependencies in a much easier way than e.g. Makefiles & Git submodules, which we've tried in the past. When combined with the Ninja generator we're also seeing ~20% faster compilation times.