Meson is much easier to use and configure for C++, being quite obviously designed specifically with C++ builds in mind. It automagically does the right thing for setting up most C++ build environments by default with virtually no config or quirks you need to learn. It is built on top of Ninja, and generally very fast and efficient. The only real knock against it is that the documentation isn't as good as could be, and it is evolving quickly, but the fact that it often "just works" doing the obvious thing makes it less of an issue. In my experience, setting up a cmake environment has a significantly steeper learning curve and is more work.

The tradeoff is that Meson takes a fairly rigorous "one correct way" approach to how you organize your builds. It doesn't prevent you from doing anything functional but what it forces you to do is very sensible, minimizes the potential for issues in diverse environments, and reduces the degrees of freedom Meson has to sort out. A prohibition on unfettered creativity, advisable or not, in how you manage your builds has turned out to be a blessing in my experience because it codifies what are very arguably best practices in code and then makes it easy to implement them.

I'm fairly agnostic on build systems -- I've probably used a dozen -- but Meson, even in its relatively youthful state, is the best C++ build system I've used so far in terms of getting things done quickly in a maintainable way that is easy to use for average programmers.