Why?
Because it's a more interesting watch if you ask me. And I feel it's better value.
I've always liked the Lange Zeitwerk and wouldn't mind a black dialed version one day, but the Zenith is a better candidate if you ask me. Then again, if you're question was for the Zenith Christophe Colomb, my vote would be hands down for the Colomb.
Tough choice! The dial is definitely more interesting to look at on the Zenith though.
Cheers,
Anthony