In terms of economic and political power (very interchangeable in the modern era), the USA, easily. They effectively have dictorial rule over the UN Security Council, and any country that disagrees with them is in for a hell-ride.

The USA is. We have the world's second largest army and the best equipped one; the UK has 28th largest. Our GDP is over $13 trillion, the UK's is near $2 trillion. Luckily, we're allies with the UK, so it really doesn't matter who is more powerful.

Technically, America is more powerful. But in reality America and Britain are both part of a greater superpower known as the Anglosphere. Australia, English Canada, New Zealand and the white English-speaking segment of South Africa are smaller segments of the Anglosphere. Basically, the Anglosphere can be described as an entity dominated by white, Protestant English-speakers. America is simply the incumbent reigning segment of the Anglosphere. It represents the westward migration of British human and technological resources and culture over a period of several hundred years where it has now developed pretty much its own character while retaining undeniable British elements. Ever notice that amongst the former colonial powers, Britain is still relatively powerful in global geopolitics. That can't be said of France, Russia, Germany, Japan, etc. Furthermore the status of English as the global lingua franca means that, in one way or the other, British domination over the world has never ended. It was simply transferred westward (like transferring money to an offshore account) and now wielded primarily by British descendents - in America! And BTW, it's no co-incidence that both the US and UK flags can be described as the red, white and blue.

Guys you all are talking about present, but after 25 years there will be only one religion ie ISLAM and gulf countries will be the most powerful. Pakistan will use the arms given by america against india, which will result in war gulf countries will destroy the world and they will be the most powerful.

The UK is more powerful because we have shaped the world the way it is today. From colonization. USA got independance from the UK not the other way around. We draw up all the african and middle eastern borders not the USA.