ASP.NET AJAX RadEditor is much user friendly (i.e. image resize with mouse, styling some simple properties like margin...etc.). We use Kendo UI and HTML5 in our new projects, but in our custom CMS we had to integrate RadEditor, because it is very smart and user friendly and gives a great helping hand and many functionalities to our users who has no html and css experiences. Kendo Editor is still not a tool for a CMS, it is good only for writing some sentences to news or for some very-very simple editing task.