I have used Linux, and only Linux, about 20 years... This my recommendation:
Stay away from the Ubuntu family if you want a good Linux desktop.
For all Ubuntu users, i am sorry. If it works for you, keep using it. I have no desire to go into "best linux distro" argument. These are just my personal opinions. And i have also used Ubuntu myself for many years, so i know thing or two.
Ubuntu package management is built in away, that forbids you to use newer software. If Ubuntu has some version Desktop environment in their repositories, then you're pretty much stuck with it. Like for the example if they have older Gnome which comes with older GTK, then there is a possibility you cannot use some newer software.
Also Ubuntu's private package manager PPA is a piece of crap. You must install a repository for each application and you're still stuck with the libraries that come with Ubuntu installation.
While Ubuntu is a free (as in free beer) software, it is not free (as in free speech). There have been multiple documented cases, where Ubuntu installations have contained shady spyware.
Ubuntu is slow. For some weird reason, there are so many services enabled by default. Perhaps it is not true for some Ubuntu based distros (i just do not know), but this is the case for the official releases. From my personal experience: after i closed services i did not need and uninstalled some packages, my cold-boot memory usage dropped from 1.2gig to 700mb.
I know, that Ubuntu is very popular. But being popular does not make it any good. Wordpress is also popular. Would you consider it any good?
While there are some nice looking Ubuntu based distros out there, most of them are not usable for work. They are not 100% stable and bugfixes may take weeks if not month. For work you need a system that is rock solid!
I personally use Manjaro Linux, which is an Arch based distro. And Arch comes with official Pacman package manager and AUR for user repositories. If there is some software available for Linux, and it is open-source, then 99,99% it is available on AUR.
Manjaro as as easy to install and use as Ubuntu. So no worries in that department.
So i recommend you to try out Manjaro. I am not saying, that it is THE best distro out there. Just give it a try!
http://i.imgur.com/0QoFiSy.png
The main difference with vanilla Arch and Manjaro are how new packages are released. If there is a new package, Arch will release it ASAP. That can make the system bit unstable. Manjaro has a testing branch and all packages are tested for weeks by users before sent to the main repository.