Ubuntu, very much user friendly.
Long Term Support (LTS) releases, such as Ubuntu 14.04 LTS 'Trusty Tahr', are not expected to present radical changes, as these should be made in the interim releases. Instead, an LTS release should add stability and polish to interim changes. Ubuntu 14.04 LTS was suggested almost three years ago by Mark Shuttleworth as the release that would see convergence across all hardware formats. In retrospect, this goal could only have been reached if the elements required for convergence — Mir and Unity 8 — had been successfully introduced in earlier releases. Although Canonical made some effort to do this, development was eventually refocused on Ubuntu for phones and tablets and convergence is now unlikely to happen until 2015. As it stands, Ubuntu 14.04 is left running X window server and the Unity 7 shell.

Well there are no new changes but it is a strong operating system. The new changes in its user interface are not bad. This is an must go with operating system.