Ubuntu it's good to start with linux it on desktop. I prefer debian (ubuntu based on debian) on desktop and servers. My web servers always running on debian Companies running servers use Suse Linux, this is famili Red Hat like as Fedora.
Talking about open source systems, before killing CentOS that was my preferred OS, now I prefer Debian.
Currently you will find Ubuntu for everything, put this distro at the end of your list if what you are looking for is security and stability.