The most powerful person in the world? hmm... this is not easy, but for sure i don't agree with those who say Trump, Donald Trump is not the most powerful person in the world, being the president of the strongest country gives power a lot of power but doesn't make you the most powerful person, for example the  congress could kick him out at any moment for any reason, because when we say Trump as long as he is president of the US we don't mean the person Trump but we mean the president of the US government who is just a 4 or 5 years employee for the service of the country and the people, so it couldn't be Donald Trump or any other president. 

Throughout history the leaders of the most powerful states and kingdoms were the most powerful persons, but not anymore, now the most powerful persons live in the shadows or at least away from flashes, even the meaning of "most powerful" has changed now, you can see it as the leader of the most powerful army and i can see it as the one who controls the media and the opinion of people for example, someone else could see it as the leader of the most powerful intelligent service, or the richest person .

In my opinion there isn't such a person , but there is a couple of persons sharing that title racing and battling each other everyone at the field which he excels at, money or finance, arms, tech, media, secret services ..etc and we can see their battle clearly in the world