I guess the best and easiest CMS is WordPress. Personally, I feel WordPress is very easy and effective way to build your website. It offers various themes and plugins which can enhance the look and feel of your website.
I've used all and it really depends on what you want to use it for. Joomla is a nice CMS and so is Wordpress.
I think Joomla is much faster than Wordpress. If you want to run it as the blogging portion of your site, Wordpress is better hands down. However; once you start adding plugins it can get kind of slow.
I recommend Kentico. It basically covers Content Management, E-commerce, Social Networking, Intranet and Online Marketing. Rate features of the software also make it a perfect tool for mobile websites, SEO, document management, online marketing tools, multilingual websites, and multisite management. It utilizes ASP.NET and Microsoft SQL Server and also compatible with Microsoft Windows Azure Platform. Currently, Kentico Development has more than 40 modules and 250+ web parts.
For a CMS I would strongly recommend on using Joomla, concrete5, Drupal, or using Grav as a good system. Others like WordPress are mostly used for blogging systems and are harder to change from a blog to a CMS system that flows nicely without having to deal with too many changes, plugins to add to remove things, or even just their general layout to change so that it doesn't scream out "blog" instead of a website.
There are various CMS platform that can be used to create a good website like Wordpress,Joomla,Drupal,sliver stripe,cushy CMS,typolight,Modx,textpattern. Among all these I would recommend to opt for wordpress or Joomla as they both are considered to be search engine friendly CMS's. It will help you in easy crawling and indexing of your website.