An incredibly popular and versatile operating system, with commercial support options and years of development behind it, Ubuntu is a great choice.
Whilst many companies will opt for more corporate options, like RHEL, SUSE or Windows, Ubuntu can be the perfect choice for various different technologies. Chef, OpenVPN, Zabbix, Zimbra, Apache, all of these products work exceptionally well with Ubuntu. Just as well, if not better (in some cases) as they do with RHEL.
Canonical, the company who make Ubuntu, are very Open Source focussed. Their intent is to produce an excellent, Open Source product, for everyone to use, whilst providing those who wish to pay the extra for commercial support contracts, with an avenue to do so.