Distros / OSs
Arch
Debian
Ubuntu
CentOS
Red Hat Enterprise Linux (RHEL)
"Red Hat Enterprise Linux is available only through a paid subscription service that provides access to software updates and varying levels of technical support."
"Since Red Hat Enterprise Linux is based completely on free and open source software, Red Hat makes available the complete source code to its enterprise distribution through its FTP site to anybody who wants it. Accordingly, several groups have taken this source code and compiled their own versions of Red Hat Enterprise Linux, typically with the only changes being the removal of any references to Red Hat's trademarks and pointing the update systems to non-Red Hat servers. Groups which have undertaken this include CentOS (the 8th most popular Linux distribution as of November 2011), Oracle Linux, Scientific Linux, White Box Enterprise Linux, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, Lineox, and Bull's XBAS for high-performance computing. All provide a free mechanism for applying updates without paying a service fee to the distributor.""
If going down the based-on-RHEL route, consideration needs to be paid towards the update delay of the distros when a new RHEL release comes out.
Scientific Linux (SL)
Oracle Linux
Quicker to release was FUD? corperate atmosphere of Oracle has a baaad relationship with the open source world in general [1]