I have extensive experience of MyPy and Pyright, even going so far as to try to fix a but in MyPy (I couldn't do it; the code is too much of a legacy undocumented mess).
Pyright is much much better. If you're starting a new project or work with people who understand the value of type hints and want to actually fix them (ha yeah right) it's a no brainer. It's also the default in VSCode which is nice. Oh and they guy that maintains it is a bug fixing machine.
The only reason you should consider MyPy is if you're adding types to a big existing project or you're working with people that don't get it. MyPy has way more "eh whatever" options so it doesn't give you a barrage of errors when you run it for the first time.
But other than that you should use Pyright. No contest.
I also have extensive experience with mypy and pyright, also even going as far as trying to fix a mypy bug (also unsuccessfully). For pyright, the dev was so responsive that I only had to report bugs for them to be fixed (sometimes in a couple of hours).
It's been a year or two since I've touched Python, but back then, Pyright, was way faster, was more feature-complete, had a much more responsive dev team (of 1). It was better literally along every metric: except that it didn't support custom extensions to the type system like mypy did. But that wasn't a huge issue since there were very few extensions, and even the one that was developed by a mypy core dev for sql-alchemy was hopelessly out-of-date, or impossible to get working. So I didn't miss it much.
I'm on the other end of the spectrum — I only write Python occasionally for smallish utility tools, just a step above shell scripts — so I'll give my input as someone relatively new to typed Python. I recently industrialized (to use the terminology from other comments here) a couple things that I'd originally done in quick-and-dirty Python 2 over a decade ago. My experience was that mypy had a handful of false positives, and pyright had none. Pyright also found one comparatively subtle mismatch that mypy didn't, although its error message in that case was incomprehensible to me.
(I also used pylint and pytest+coverage.py; interested whether there are better choices for next time.)
Pyright is much much better. If you're starting a new project or work with people who understand the value of type hints and want to actually fix them (ha yeah right) it's a no brainer. It's also the default in VSCode which is nice. Oh and they guy that maintains it is a bug fixing machine.
The only reason you should consider MyPy is if you're adding types to a big existing project or you're working with people that don't get it. MyPy has way more "eh whatever" options so it doesn't give you a barrage of errors when you run it for the first time.
But other than that you should use Pyright. No contest.