I own both the Zeiss and the Monarch. (as well as the Elite 4200, and Leupold Vari-X III). I mention these 4 brands because they seem to be in the same league.
I think that the Elite 4200, the Zeiss Conquest, and the Nikon Monarch are VERY VERY close when it comes to optical clarity, resolution, brightness, etc. Suprisingly, my Vari-X IIIs are last in the optical department. Leupold's have an excellent reputation for reliability and I have never had a problem with them. Then again, I have never had a problem with ANY of the 4200s, Conquests, or Monarch either.
If you were to make me close my eyes, then put either the 4200, Monarch or Conquest right in front of me eye, I honestly would have a very hard time telling you which one is better.
Zachary