First I choose Ionize because it has good interface and installation was very easy but when I started looking inside the code I saw a big mass. Admin part interface realize with using Mootools as a js framework and MochaUI as a user-interface. So all admin part made by ajax request so I didn't like it because ajax request don't do one big js engine. It happens this way you press link -> js calls ajax request -> it receive big part html with js and change some html that exists with received data. So I stop go forward. Thanks Ionize with it help I watch many information about Mootools and really like plugins.
So after disappointed about Ionize cms I start looking into the code of Halogy cms. It has HMVC patter that I never met (like MVC but groups in folders as modules). So from the beggining it was easy and clear to understand. Code clear and has many comments so I like it. If you want learn CI framework you should look inside this cms.P.S. I think CI is best framework for small websites or for programmers that like writing websites on clear php. For big project I think CI doesn't suitable. CI also gives freedom in writing code, its very easy for beginner, have good documentation, but it has very small functionality versus frameworks like Yii CakePHP...