I use funtoo for my personal server... It's partly because I've used gentoo for so long that I understand it well and I find it very easy to mainting. I also love the fact that it's just easy to install newer versions of any software I need which is great for development and testing (which tends to be more of a problem with ubuntu and debian in my experience where I often end up having to compile from source). That said while I use funtoo on my server, I use ubuntu LTS on the servers of my clients. It's just much easier if there are other people working together.

I used to use gentoo for my laptop and desktop until I switched to Mac and while I do like Mac OS X, I kind of miss the freedom I had with running gentoo. I enjoyed spending hours to scripting fvwm just the way I liked it :-)