No, it isn't simply a matter of preference. The style used by CodeIgniter simply is wrong in my eyes (yeah, give me many downvotes pls). There simply is one coding style that many projects use, the Zend Coding Standards Coding Style. In my opinion this is the only valid coding style, simply because most projects use it and you therefore don't need rethinking when you start contributing to them.
Actually, this is one of the reasons, why I do not use CoedIgniter. Another reason is, that they provided the introduction videos only in QuickTime. I don't expect they provide me a webm video, but at least Flash would really be nice.
PS: Please don't think I say this only because these are the Coding Standards I use. No, this isn't the case. I do not strictly adhere to these standards. But I think I should and I will try to. Simply because they are the standard.