When I had to take charge of the CMake files of gtk-fortran around 2015, I bought that book:
Ken Martin, Bill Hoffm, Mastering CMake - A Cross-Platform Build System. Kitware, 2010, ISBN 978-1930934313.
I read the 234 pages of the chapters, the 460 following pages being the reference manual. And that was very helpful…
I am satisfied with CMake for that project, as it can be built under Linux, macOS, FreeBSD, and MSYS2/Windows. It does the job. My only problem with it, is that its syntax is painful (2 miles long options…).
I tried to replace it with Meson, but was blocked by the .mod installation issue. Apart that problem, Meson is really impressive, with its Python-like syntax.
For personnal projects, I am happy with the actual fpm, and I am sure it has a bright future.