What are the best C++ package managers?

Hunter is a CMake driven cross-platform package manager for C/C++ [1] projects. With the help of Hunter you can organize builds for Linux, Windows, macOS, iOS, Android, Raspberry Pi and other platforms. Third-party external projects are highly customizable, effectively allowing you to have myriad variants of directories with them based on combinations of version to build, static/shared, CMake -D options, Release/Debug, etc.