Hu Jintao as an individual has few effective powers, and I'd say he's individually less powerful in his country than even Obama. All important Chinese government decisions must be approved by consensus by the Politburo Standing Committee.
So, while Hu himself is less powerful than Obama, the nine-member Standing Committee collectively has way, way, way more power than Obama, all of Congress, SCOTUS, and all three letter agencies combined.
It's an open secret Putin has been a Tsar since seizing power in 2000. Also, Merkel has plenty of power not just over Europe bu the whole world. Abdullah is a
I'll say therefore it's like this:
1. Vladimir Putin
2. Barack Obama
3. Angela Merkel
4. Francois Hollande
5. Hu Jintao
6. David Cameron
7. Zhou Yongkang *
8. Abdullah
9. Xi Jinping **
10. Sonia Gandhi
* Chinese Politburo internal security chief, widely seen as a loose cannon and hardliner who isn't afraid to take sides
** Hu Jintao's successor, thought to be a target of Zhou
And yes, I'm bending the rules by naming three Chinese Politburo members. But Politburo members are called Party and State Leaders by the Chinese state media, so I didn't break the rules.
What's telling is that nobody has listed Yoshihiko Noda so far. I actually had to use wiki to find out who the current Japanese prime minister was, which goes a long way in terms of explainig why the
In Japan it's widely known that real power lands in the ruling party bureaucratic leadership rather than the Prime Minister. Hence, the insanely high turnover among the political class.