English language is powerful of course, but the most powerful one I think is Chinese. It's a language of the future.
Why?
What do you mean by powerful to start with? English is the most spoken language used because of Europe, the English Commonwealth and the Brittish former colonies spread around the world, also in Europe many nations from different language families have many common things with English, as it unifies vocabulary from the Romance and Germanic language trees, which already covers most of the continent, also most things were developed in the United States specially on the internet, etc. There is no such a thing as "powerful" but accessibility, that's why people started using English.