Some will say better hardware support. While Linux has better hardware support, i usually find this to be in the more exotic direction.

I think it's simply down to Linux being where the money is. The big players (IBM, Dell, etc) are all actively promoting Linux, and trained personel is also somewhat easy to find. So Linux is "the beast you know".

As for FreeBSD, it might be a technically better platform, but it is living in Linux' shadow.

Personally i run FreeBSD for the excellent documentation, stability, features like ZFS, but nothing i run couldn't just as easily run on Linux.