I'm a professional PHP, Python and Javascript developer from the UK. I've worked with Django, Laravel, and React, among others. I also maintain a legacy Zend 1 application.
I have used both to some extent, and I personally prefer Psalm over PHPStan, largely because I found it was better suited to legacy code (it was built for Vimeo's legacy code base) as a lot of my work is on a messy legacy application and it's had the ability to set a baseline for existing code right from the start. But vim-ale supports both so there's no need to switch if you want editor integration.
From school dropout nad part-time homeless to developer with experience in science (Max-Plancks-Institute by Göttingen), Insurance (Check24) and now as contractor/freelancer in various fields.
I have used both to some extent, and I personally prefer Psalm over PHPStan, largely because I found it was better suited to legacy code (it was built for Vimeo's legacy code base) as a lot of my work is on a messy legacy application and it's had the ability to set a baseline for existing code right from the start. But vim-ale supports both so there's no need to switch if you want editor integration.
Then I final thank you. Have a productive week ;)