I'm planning to get a more detailed comparison with languages in the same space. Kit and Zig overlap quite a bit; the main difference I see is philosophical. A major goal in Kit is to be concise, expressive and eliminate boilerplate; Zig perfers to be straightforward and readable, where a function call at runtime always looks like a function call in your code. Term rewriting and implicits are examples of features in Kit that probably wouldn't be implemented in Zig. Also, Zig aims to replace and compete with C, Kit just wants to leverage it, so the scopes are quite different.
Zig is awesome - I've used it and would use it again, I'm funding the creator on Patreon, and I see these two languages as filling slightly different niches and having different pros and cons.