Xmake gets posted here once in a while, here are some previous discussions:
https://news.ycombinator.com/item?id=19610459
https://news.ycombinator.com/item?id=19610459
Xmake's biggest advantage: it's a single binary (vs Meson requiring Python)
Meson's biggest advantage (aside from popularity): it's a declarative DSL rather (vs including a full-blown programming language like Lua in Xmake)
(The second point is subjective, I know some think that including a full programming language is a strength but to my eyes it's a downside that largely outweighs the Python dependency.)
I personally don't consider this an advantage. We've ran into the limitations of a DSL way too often at work and at this point I prefer just having a plain programming language as an interface. This way you don't have to learn a custom DSL with its own quirsk, you always have the escape hatch of just writing custom code, and it tends to be less quirky.
It is actually pretty useful to have installed alongside meson, even if just for access to the manpages as documentation.