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.
I have a feeling the OP meant influential instead of powerful. I will keep things to myself as to why powerful was selected though. I definitely think English will continue to be the most influential language out there since it is already deeply connected to the international trade system. And it will long continue to had influence as a number of languages incorporated words into them.
I know a lot of people try to equate Han Chinese to the PRC's level of importance, but all someone has to do is look at Russian to see where Han Chinese is going to go. Han Chinese is also incredibly difficult to understand and speak. Just live in the PRC for a few years and you will be come frustrated trying to speak from people from the different provinces.
Then there is the fact that English is something taught in the PRC. Their English level is terrible because of the terrible quality of the English teaching programs, but even an average young Chinese will be capable of basic communication in English.
Like it or not, English is the international language.