[keithasaurus]

mypy is essentially the reference implementation. pyright probably is better as a type checker, but, for the referential aspect alone, I suspect many libraries will continue targeting mypy.

One potential benefit of mypy is that it comes with mypyc, a compiler that leverages mypy's evaluation of types. Since pyright and mypyc are not exactly equal, it makes sense to use mypy if you want to use mypyc.