English. I love the English language. I remember my very first English lesson at school like it was yesterday. It was almost like an epiphany to me. It was so easy, I had a feeling like I already knew everything the teacher showed us. Of course it was the teacher's proficiency which made it so easy for me. For our very first lesson, she draw little pics/icons of nouns which are the same or very similar in German and English on the blackboard. For example finger, ring, house/Haus, hand, mouse/Maus and so on. I knew from the very first lesson that this was what I wanted to do, what I wanted to learn, and learn it well.
It showed I have a talent for it and I did learn it well, but since I've never lived in an English speaking country I'm still not as good as I'd like to be.
On a more practical note, it would be more reasonable to choose another language than English. I already am able to communicate in English, but I'm not able to do so in a third language. My second choice would be Spanish.