Shower thoughts: TvZ is the only match up including mirrors which utilizes every single unit of both fractions in a meaningful way. All units are important and key in different games, situations or strats. Also not just the units, but every spell (kind of) and all the researchable abilities too. Someone may say that the Infested Terran and the Ghosts are not really used which is true, but this is the only match up where the infested terran can even appear and the ghosts are as bad as vs anything else.

So I think we can say that TvZ is the most complete match up in the game