[Xymon] why do you use xymon?

Would any of you mind telling me why you use xymon? I have a co-worker who is pushing hard for zenoss, and his arguments include "gui discovery tool", "no hand editing of config files", "it is an enterprise level monitoring system and you can buy support and bring in a consultant to set it up for you", and the ever popular "everyone is using zenoss now".

Elizabeth Jones