In my domain (bioinformatics), if it's self managed, Ubuntu is the standard. I would attribute much of the popularity to the Biolinux project, which built upon

In my domain (bioinformatics), if it's self managed, Ubuntu is the standard. I would attribute much of the popularity to the Biolinux project, which built upon Ubuntu LTS and bundled in many popular bioinformatics packages which are a pain to setup and configure on your own. Besides these, many popular packages provide deb bundles, which makes it easy for a PhD student to manage on their own.