Freebsd, started on the stuff and never switched.

CentOS 4.4 and Redhat Enterprise over here. Common operating systems, easy fixes and pretty stable.

We use Cent OS on most of our servers but I like RHEL to it just costs to much.

Err...Cent OS effectively is RHEL minus Red Hat branding.

I use Windows, FreeBSD, and CentOS. I cant seem to get away with just one. I like Linxu the best!

While two of the servers I am on run on Linux, one of the VPS servers runs Fedora Core 4.

CentOS for servers, Ubuntu at home, and FC4 on the PS3.

Got to go with Cent OS and Debian.

All of our web hosting servers run FreeBSD, our VPS servers run off CentOS.

we Use linux Enterprise

CentOS 4.4, won't use anything else (not even RHEL)

Surely you would just use whatever servers OS makes the most sense for your market and service?

I think most web hosting customers want choices depending on what they want to deploy. Other than that - if you want Linux, then CentOS is excellent. Windows? Well you have the choice of Windows 2003 Server and ... well... thats it really

Personally, I enjoy using centOS 4.4. Fedora Core 6 is ok too. For personal OS, I like using Ubuntu.

FC5 and CentOS for me

I think that freebsd is the best one.