I like the app uninstaller included in Forklift. You open Applications folder, and delete an app. A window appears with all the associated files Forklift can find (which is extremely accurate, BTW), and you can uninstall everything you want from there.
replyFor .pkg files, there's UninstallPKG which reads the package manifest and properly uninstalls it.
I would like to take this moment to rage against Apple for shipping that package installer, literally 25 years ago, and never once having apparently even considered a native, out of the box way to uninstall programs that were installed that way.
replySpeaking of packages, even more embarrassing, Microsoft Windows literally beat them to shipping a first-party package manager. I feel like Apple lives in a fantasy land that the drag’n’drop app install method from the classic macOS is some kind of platonic ideal — never mind that they can’t stop half the apps out there from going outside that paradigm and installing their crap all over the place.