Most of the things in an autogenerated Makefile are there for a reason: dependency tracking, stuff like "make help", proper cross compile support (trickier than you think!), test running, dist, distclean, configure flags... You could reimplement them yourself, but you're going to end up doing a whole lot of work for little gain.
I'll write Makefiles by hand for small C/C++ projects, but for anything serious I'll use cmake/etc.
Source: We made a "properly hand-tailored Makefile" for Rust. It started out short and elegant, but it quickly grew into a nightmare lasting 4 or 5 long years. Only about one or two people (Alex Crichton and Brian Anderson IIRC) had any clue how it operated. Proper cross-compiling support involved multiple levels of nested variable expansion all over the place to find the right build/host/target compilers so that Canadian cross builds worked. Alex ended up doing some heroic effort to throw away all the Makefiles and going to (effectively) a custom build system using Cargo, which was a massive simplification.
I've been told that, before KDE switched to CMake (becoming the first big open-source project to do so), there were only two or three people (out of hundreds of developers) who dared to touch the autotools stuff, except for peephole edits like adding a new source file to a list. For everything else, one of the experts needed to be brought in.
I only came into KDE when the switch to CMake had already happened, and remember it as reasonably approachable (even if quirky). Most developers were familiar with it and actively authoring the CMakeLists.txt files for their own projects. (That doesn't mean that there weren't some experts again, but they focused on implementing reusable modules that the others could easily integrate into their own build system.)
I'm already struggling to compare variables to strings. Sometimes the string will be interpreted as a variable instead of a string, and I don't know how to avoid that.
Most of the time in CMake, you want expansion, so:
my_function("${MY_VAR}")
Avoid the quotes if your variable contains spaces or other separators, and it's your intention for the separate pieces to go into the function or macro independently.
The other case is builtin macros that expect to be passed the name of a variable that they themselves are manipulating. For example the list and string operations. See: https://cmake.org/cmake/help/v3.0/command/list.html
I'll write Makefiles by hand for small C/C++ projects, but for anything serious I'll use cmake/etc.
Source: We made a "properly hand-tailored Makefile" for Rust. It started out short and elegant, but it quickly grew into a nightmare lasting 4 or 5 long years. Only about one or two people (Alex Crichton and Brian Anderson IIRC) had any clue how it operated. Proper cross-compiling support involved multiple levels of nested variable expansion all over the place to find the right build/host/target compilers so that Canadian cross builds worked. Alex ended up doing some heroic effort to throw away all the Makefiles and going to (effectively) a custom build system using Cargo, which was a massive simplification.