I think it's best to be OS-Agnostic. Who cares what operating system you're using? Learn how to do your work on any and all operating systems. That being said, if you're in a position to decide the architecture of your networks, go with what you feel most comfortable with in terms of workflow, what will satisfy the business requirements, and what your organization as a whole can feel proud of.

Also, do not be afraid to suggest a mixed environment, pulling the strengths of each operating system and method to create a really rock solid network.

I really am impressed at the lack of saber rattling in this thread.

I totally agree with your great advice, Triflin.

Better is so subjective there is no real answer. What's better, oranges or apples? Grapes or plums? Carnations or a lily? In the end you're better off running a server you are comfortable administering and upgrading.