Dietrich Schmitz, writing for the Linux Advocates website, posted an article yesterday about how Red Hat's adherence to the Linux Standards Base (LSB) guarantees stability and reduces costs in the enterprise. While I agree with Mr. Schmitz wholeheartedly, from my perspective the reasons by Red Hat Enterprise Linux remains both the leader and the best choice in business, government and non-profit spaces goes far beyond the LSB.
I've been a professional UNIX/Linux systems administrator for 18 years now. I've had to implement, maintain and support servers from all of the enterprise distributions and a few distributions not generally used in the enterprise as well for my employers and customers over the years. I'm a big advocate for Red Hat and the various free clones (CentOS, Scientific Linux and Springdale Linux) as the best solution for most organizations. First, it's exceptionally stable as Mr. Schmitz points out. Second, it offers the longest support period at 10 years. Third, they have excellent and professional support.* Fourth, they do the best job at insuring compatibility with both FOSS and commercial apps during the full 10 year release cycle.
My big issue with SUSE Linux Enterprise (SLES/SLED) is that they do push major version changes of the kernel, tool chain and apps in what they euphemistically call Service Packs. The Service Packs are actually major releases recently and have been known to cause major breakage and pain. My experience with their support organization here in the U.S. has been less than satisfactory, particularly the time needed to respond to and resolve issues.
Canonical (Ubuntu) has much shorter support periods than either Red Hat or SUSE. They also don't backport additional hardware support or patches into their kernel, forcing you to either do the SUSE style update gamble even more frequently than with SUSE or else to run without needed support and/or vulnerabilities.
The free clones of Red Hat Enterprise Linux I mentioned earlier are not permitted to name their source, referring merely to "the upstream provider," but pretty much everyone in the Linux community knows precisely what they mean. They represent a real advantage to Red Hat (the distribution if not the business) in that they allow businesses to try before they buy. They provide the opportunity to run a test bed or non-critical system at reduced cost. The clones also allow non-profits and cash strapped small businesses to forgo commercial support, at least for a time, and still use software that is entirely compatible with the leading enterprise Linux distribution. As organizations grow and their needs change converting a server or workstation running a clone to a genuine, supported Red Hat system is a simple process.
Finally, I'm sure fans of Debian and Slackware packaging will disagree with me, but keeping to standards, specifically the LSB, also goes a long way to insure application compatibility. I think it's vital that all enterprise distros follow standards.
*= Disclaimer: I was part of the support team for seven months as a consultant in 2005. I no longer am affiliated with Red Hat in any way, shape or form.
[NOTE: This article originally appeared as a comment on LXer.com in abbreviated form.]