I am currently running Fedora 16 on my laptop, which is like 3 years EOL-ed. The reason that's the case is because it is not easy to upgrade to the current version in Fedora (at least v16) and it requires a complete reinstall.  So everything on it it old and doesn't work too well and I am just too lazy to move my data on an external medium and rebuild the OS. Ideally, I would like to upgrade by running a simple yum/apt-get command.So my lesson learned from this experience is that I would like my next Linux distro to be idiotically easy to bring up-to-date, not because I am incompetent to deal with Linux but simply because I am lazy and want to remain so.  I also believe that, in this day and age, OSs should be very easily upgraded.What Linux distros make upgrades easy to conform to this agenda?  I specifically do not want to have to move the data or the file system to a separate medium before performing the upgrade.I also would like the distro to support KDE, which is my preferred interface.
What Linux distros make upgrades easy?
distributions
Debian is probably one of the easiest to upgrade - even across major releases.From the Debian FAQ, Chapter 9, Keeping your Debian system up-to-date there is this statement,A Debian goal is to provide a consistent upgrade path and a secure upgrade process. We always do our best to make upgrading to new releases a smooth procedure.Opinion: I have just upgraded a number of systems from release 7 (wheezy) to release 8 (jessie). For the most part it just worked. One had previously been upgraded from release 6 (squeeze). This is one of the major reasons I prefer to use Debian.More information in answers to the Question Will Debian Wheezy (stable) automatically upgrade to Jessie once Jessie becomes the stable releaseUpdate: since you have amended your Question to indicate a preference for KDE, you might like to review KDE's software in Debian and these Live install images