My experience are, that zonal marking is/was everytime better against equal/stronger teams.
Every match I used mtm vs an equal/stronger team, I conceeded 2 oder more goals and lost all of these games. I also lost some games with zonal marking, but my statistic says:

8 (mtm) vs 2 (zonal)

So I only use zonal (vs weaker teams(, because of saving condition.