Windows and Mac OSX are much the same when it comes to 'servers for idiots'.
Before i get trolled too much, I don't mean that in a negative way. I have worked on everything platform from super computers, from Cray's down to netbooks!
Windows and MacOSX (in the same way as OS/2 in the past) took many of the decisions away from the user, so making a server/network available to non-techies in the way Novell and AIX never could.
LINUX platforms (or generic UNIX based servers) are a continuation of the Novell type of platform. They are great at what they do, but need a good deal of knowledge to setup and configure, so are out of reach of most mortals
MacOSX is based on a old branch of UNIX but retains many original UNIX commands and controls. The good thing about MacOSX Server is that you can use the 'idiot' method GUI front end, or you can get down and dirty in the command lines.
Windows is much less able to do this. OSX Server is cheaper software, but hardware is expensive against a Windows box... but the actual RoI (Return on Investment) of a Mac Server is actually not far from that of a equivelent Windows server. Don't think you can compare a CostCo PC against a Mac Server. They are engineered differently. Try thinking IBM x-Series vs Mac Server and the prices don't seem too far apart!
So, the answer to pretty much every technical question about 'what is better... A or B' is that there is no better, just different.
Again, the RoI of a Windows 2008 Server vs a Mac OSX Server vs a LINUX RedHat EL Server is roughly the same for each. They each serve ('scus the pun) different purposes in life so choose the one that suits you best, or you prefer the look of, or have shares in the company, or just want to own the T-Shirt