https://www.kernel.org/
you should use the most recent version (3.8.10).

Well I know what you meant and probably does everyone else. But I just want you to know that Linux itself is just the kernel which on it's own is pretty useless for an enduser. And therefore asking for a version of Linux is misleading.

You are searching for a GNU/Linux Distro that suits your needs. Although I do think gentoo is the best to use, it's probably not the best for you.