Strongly disagree. Kohana is, IMO, rather poorly designed (while rewritten, it's still fundamentally all too similar to CodeIgniter for my liking). There is not a strong focus on security[1], there is not a strong focus on modernity--it's inexcusable to not be on PHP 5.3 today, and while Kohana will run there it does not understand PHP 5.3 idioms and features--and the code quality, after auditing, is not all that impressive.

Symfony2, on the other hand, puts a fairly strong emphasis on security, is fully based around PHP 5.3 idioms, and is written with sparkling code.

[1] - http://dev.kohanaframework.org/issues/2766 comes immediately to mind; forget the resolution of the bug (such as it wasn't), the behavior of the developers is not good. I get the feeling from those who've used Kohana that this isn't a unique situation.