For my current project in C++ I just use cmake. It works fine on Linux, Windows, FreeBSD & OpenBSD, spits out stuff that integrates with the native/most commonly used build environment on the respective platform, provides facilities for config, build & installing, and if you avoid all legacy cruft it's even somewhat decent.

Currently, I use scons for C/C++ projects, though with a decent amount of stuff built on top of it. When I realized that I had a rudimentary package manager in it, I started thinking that maybe I should go searching for something that already does what I need.

I've used make quite a bit, and it is doable for individual projects. Where I start having trouble is managing libraries that may be used across multiple projects. When a library needs to supply its own configuration, and be subject to configuration specified of the project using that library, things get rather complicated, which is why I turned to scons.

> It'd be interesting to hear everyone's go to build tools.

A script written in whatever the primary language of the project is (usually with some library support), ideally; to reduce the minimum required knowledge to be a first time contributor to the project. Some kind of js build tool for js projects, fake for f#, and so on. I don't want people to need to learn "the one build tool DSL to rule them all" (be that makefile syntax, bazel rules, or whatever) to contribute to a project's infrastructure, on top of the project's primary language.

So for C? Fortran? You'd have users of those languages use those languages to write programs to do the build? But then, how would you keep them from generalizing their good ideas about builds into some kind of... system?

That is a good way to have your build system expand until it can read email.