The two analysers have different defaults and different opinions about the same code, and running both is rarely worth it.
PHPStan levels 0-9, one axis. a baseline. extensions
for every framework. easier to adopt.
Psalm per-issue configuration, taint analysis, and
a much stronger generics story. steeper start.
both duplicated configuration, contradictory
findings, and two baselines to maintain.
pick one. the second one's marginal findings are not
worth the second configuration file.
Psalm’s taint analysis is the one genuinely differentiating feature and matters for code handling untrusted input — it tracks a value from source to sink and reports the ones that reach a query unescaped. That is worth a second tool for a specific audit rather than as a permanent fixture. For everyday use the choice is mostly about which one the team will actually keep at a high level.