There are many different PHP frameworks – each with its own merits and ldemerits. Selecting a PHP framework can be an intimidating task but we have significant experience in PHP to distinguish what constitutes a good framework or and what does not. PHP frameworks are tools that can be used to save time and streamline coding.
Choosing an inappropriate PHP framework can create complications in the long run leading to prolonged development time and other concomitant problems. Yii Framework and CodeIgniter are arguably the two frameworks most widely preferred.
CodeIgniter is indeed a simple and yet comprehensive framework though it is not wholly helpful when it comes to adequate support for templates, user controls (or widgets as they are known in Yii), integration with jQuery and few other less significant things. CodeIgniter has a massive user community and ample resources to learn from.
While CodeIgniter is simpler, faster and handy, we use Yii selectively for development of applications with heavy traffic flow – such as portals, forums, content management systems (CMS), E-commerce systems etc.
Yii is no doubt a very solid PHP framework and versatile and as such it has a massive codebase. It has excellent documentation and you can always inspect the code yourself. It has used some of the salient concepts from ASP.NET and from many other frameworks.