I'm not sure if MtM really has an equivalent considering how many songs that were finalized or nearly finalized have already been released. We know 17 songs were considered for MtM, leaving 5 cut from the album, but it's either possible we've heard all of them OR there's 1 left unreleased. No Roads Left, Blackbirds, Across the Line, What We Don't Know, are 4 of 5. The fifth could be Pretend to Be, Chance of Rain, Not Alone, or Ammosick/The Last Line.
Grecian was never finished, and they stopped working on it in favor of QWERTY. Fire in the City got scrapped and some of it was reused to create Given Up. That leaves Chester's version of No Roads Left as one of the only unreleased songs with vocals left that we know of for a potential MtM20.