On macOS, is it preferable to install the VST3 or AU version?
Audio Unit (AU) is Apple’s extension for plugins in its DAWs like Logic or GarageBand.
VST3 is the extension commonly used by all other DAWs. Many DAWs (not Apple’s own) also accept the Audio Unit plugin on their system.
Both extensions have very similar performance. But if you don’t plan on using Logic or GarageBand, then the VST3 extension is all you need.