[tthayer]

I'd venture to say "The one you know best". If you find yourself struggling to do something in the language of your choice, see how others are accomplishing it and then decide.

[makufiru]

In this case, I'm actually using game dev as the excuse or motivator to learn a new language. So the one I know best doesn't necessarily apply here. Haha

[mlitchard]

In that case, check out Reactive-Banana, after learning some Haskell.