Creator of Zod here. I wrote up a blog post comparing Zod to the other popular object schema validation libraries (yup, io-ts, joi): https://vriad.com/blog/zod. I don't address the various JSON-Schema validation libraries since none of them have static type inference, which is (imho) the killer feature.
Looks really cool!
We're currently using io-ts, and the one thing that bugs us the most is it's less-than-optimal error-reporting. Especially for complex/nested objects, the error messages produced are pretty much useless. The functional aspect of it is something that we kind of got used to - and mostly hide by having a few wrapper-functions.
Just published an update to Zod that overhauls the error reporting. Now you can get the exact location in your complex/nested object where each validation error occurred. Plus all detected validation errors are reported simultaneously instead of just throwing an error at the first sign of trouble.
If you decide to switch to Zod keep me posted and don't hesitate to reach out with any feature ideas