Checklist in this comment: #2503 (comment)

The specific features I am thinking that Autoconf lacks are

• Windows support (with and without mingw)
• Outputs Ninja or something similar

Both of these are non essential, but good for various experiments:

• Windows support obviously allows experimenting with Nix supporting windows. GCC is inadequate because it doesn't offer C++ interopt with MSVC, so Windows's many C++-only APIs are unusable.
• Outputing a dependency graph allows fun experiments with Recursive Nix (edolstra@1cfdfd7) and ninja2nix (https://github.com/awakesecurity/ninja2nix)

This lowers the list down to Meson and CMake, AFIAK. I prefer Meson because:

• It doesn't use compiler makefile generation, which avoids a regrettable ninja impurity
• It's less crufty. CMake became better, but old cmake was bad, leaving a lot of legacy cruft. Meson is a clean slate so there's no minefield of deprecated bad ways of doing things.
• Full disclosure, I've been working on improving Meson's cross compilation support, so I'm partial to it.

CC @taktoa