I spent quite a few hours a while ago trying to organize languages into different language groups in order to pick which languages to learn next. If you're interested in that see the blog post that came out of that: http://hacklash.posterous.com/how-to-choose-your-next-progra... .

Just be warned that I'm coming at it from the outside with most of these languages, to make your final decision try and find someone experienced in multiple languages from the paradigm and ask them which to learn the paradigm with.