MKV is the format that hoards: video, a dozen audio tracks and every subtitle, all in one box. It was born in 2002, the open-source Matroska project, and its real weak spot is playing on TVs, iPhones and editors that never learned to open the box.
WAV is audio with nothing taken away: every sample intact, every megabyte accounted for. Raw PCM samples in a RIFF wrapper. No compression of any kind. That makes it the right destination when what you need is recording, editing and mastering, where every last bit matters.