We are big fans of Mark Shust's Docker Configuration for Magento project. We use a lot of our projects, the ones we start from scratch as well for ones that we have taken over and have some weird setup in place that we simply cannot get to work.
Back at #mageuc19 I gave a talk about various PHP tools that help you to manage the quality of your (Magento) project. One of the tools I mentioned is CaptainHook, a tool written in PHP to manage your git hooks. Whilst this is not a QA tool per se, it still made sense to showcase it as most QA tools do run via CaptainHook in our projects. That means tools like PHPUnit, Codesniffer, Security Checker or tools like PHPStan or Psalm.
These days we get more and more in situations where we have to push our code into Git repositories of our customers, either because the customer wants access to the source code or because we are working closely with their in-house team. Maintaining our own local copy of the source code and constantly keeping our copy in sync is a no brainer with Git.