Ck77 is definitely right.
I would go for the Zenith.
But seeing that the 2 choices provided is quite contrasting.
The Zenith Chronomaster Open Reserve De Marche is a dressy watch.
While the Omega Moonwatch is as sporty and robust as they come having been tested by NASA and approved for all manned space mission.
Of course until recently, the Felix Baumgartner stratosphere jump sort of shake the Moonwatch mantle abit...
For me, if you pit these two "brands" side by side, I would go for Zenith.
Reason is that for almost the same amount of money, you get an all in house legendary chronograph.
A watch that is less "common" than a Moonwatch.
But like I said, it's just me.
Of course some might argue otherwise but in the end, it comes down to your preference.
Both watches are awesome in it's own right... just boils down to which one you would like to wear day in day out...