I have been using ubuntu for a while. In fact, the last Linux box I had prior was Fedora 10. My current primary linux box is running Ubuntu 10.4 (a bit outdated). I recently upgraded to 12 and found some performance issues on my dual core Dell Box. The majority of my development Virtual Box images are Mint Linux , I think version 14.
These are the virtual machines that I use for development for WordPress, drupal, and other server development systems. My Magento dev box is also running mint.
It seems that I have heard of more people switching to Mint from ubuntu recently. I am unsure of reasons, but it seems that a general frustration with Ubuntu and also some performance complaints. I had decided to give it a try based on some discussions over at hak5.org. Since then, I’ve just determined that it seemed to run faster than the ubuntu 12 systems.
What is your Linux Distro preference? For a long time Ubuntu was the reigning king, now that may not be the case. For those who are interested, Mint was a forked version of Ubuntu.