I run a small web development company in the states. Two months ago we sat down and tested just about every OS we could get our hands on, looking for the perfect workstation environment for LAMP development. All of them had their pros and cons. We eventually settled between PC-BSD (FreeBSD) and Kubuntu (Linux).
PC-BSD / FreeBSD was actually the winner by far. KDE ran much much faster than on other Linux distros, the ports system works better for developers, we had less stability issues while testing all of the tools we typically use. We've come to the decision that PC-BSD with virtualization support for Windows and Linux - both for QA and for software packages like Adobe Creative Suite - is best suited for an agile development web development firm.
Unfortunately, we had to use our second choice, Kubuntu, because VMWare only supports Linux at the moment. However, after how impressed we were with PC-BSD and how well it meshed with our development process, we will certainly consider using an alternative to VMWare for our Windows and OSX support if a suitable one arises, despite how pleased we've been with VMWare in the past.
