I've always gone for the ones who really knew one language inside and out. The reason is actually very simple, they have demonstrated exceptional skill to dive deep into one language, so they should be able to do the same in another language.
The jack-of-all-trades people usually are much riskier hires as they don't always understand how deep they can go in any particular language, thus are unable to fully assess what they don't know, and require much more guidance as a result.
The jack-of-all-trades people usually are much riskier hires as they don't always understand how deep they can go in any particular language, thus are unable to fully assess what they don't know, and require much more guidance as a result.