Which is the most popular CMS ?

Everyone should choose your on based experience and knowledge about each of them. Important is purpose of the page, kind of information which we want to load, installation process, manage and other elements. I agree that WordPress has very strong position among internauts and excellent opinion. But is not mean that we should delete other CMS. Worth is before checking all and after make a decision. I did this with Artisteer and you also recommend do it.

Which of these platforms is best really depends onwhat your particular needs are for the site in question. Consider what you are trying to accomplish first and then decide which platform is the best. If your primary purpose is to share your views or info with visitors then WordPress might be the easiest choice. If, however, you want to build a more custom interface, perhaps with events calendars, polls, photo albums, custom forms and so forth, I would choose Joomla or Drupal. If you need a very high degree of control over the data on your site, I would go with Drupal. In many cases, it will be possible to do what you want in any of the major platforms, but some of them are better suited to particular tasks than others.

Wordpress is the most popular CMS.
It has a strong, global and vibrant community
The user interface is comparatively easy to use
It has a wide-ranging list of modules, including for mobile, which is matched in numbers only by SharePoint
Tend to be cheap to implement and host

I think WordPress is good and there are millions of plugins are available which helps your site and reduce almost your work.

The most popular is of course .. Wordpress a lot of sites are also raised on Joomla and Drupal. From my experience I can recommend you try a CMS called Concrete5 is less popular than these few solutions above, but very underrated because in many respects it's better and easier than Wordpress.. really! You should try it

On top of being the most popular, WordPress is really also the most flexible due to its wide range of supported plugins - with more being developed every day.

you already answered your question, wordpress is the clear winner and the reason behind that is 1) more stable 2) more themes 3) highly customizable and easy to use

WordPress is the most popular CMS. The main reason behind this is that it is extremely user-friendly. Moreover, there are various WordPress themes, plugins and extensions for making the WordPress website highly efficient.

Wordpress is great, it does everything you want it to do so long as you install the right plugins. There can be some improvement however on how things are run in the background, as Wordpress tends to get extremely slow.