GCC (including G++ and Gfortran) on Windows is available via several means. We generally prefer MSYS2 for using GCC and numerous libraries with pacman package manager. MSYS2 and WSL have active and competent development teams. We find MSYS2 to almost always work for our needs. For the few difficult corner cases, we use WSL. The other projects are also competently maintained, but MSYS2 or WSL are generally the most up to date by far.

MSYS2

(recommended, well-maintained and very up to date

WSL

recommended for apps needing Linux system API

MinGW

what MSYS2 uses internally

Cygwin

usually WSL is preferred instead for better performance

TDM

usually MSYS2 is preferred instead