Well Obama can be voted out and probably doesn’t really know what’s going on inside the secret security agencies, which puts him 3rd.
Chinese politics is a complex animal, but I think the Party is a very stable and mature system, which effectively controls the distribution of power. If the Party wants rid of one of it’s members, they’re not going to last very long, even if it is the Paramount Leader. I’m not sure how much power Jintao has at his fingertips, probably more direct control than Obama, but he’s not President-for-Life, he is a servant of the Party. I’ll place him second.
Putin’s personal power is evident from the fact that he is apparently in complete control of his party, which consistently “wins” the “elections”, effectively “uncontested”. He didn’t try to change the constitution to allow him to be continuously President, but he has otherwise arranged things to make this unnecessary. He became prime-minister, and the practically installed his own president. And he still takes centre stage. After this term, he will become President again. He has lots of “friends”. He is well-aquainted with the oligarchs, who control the vast majority of Russia’s wealth. He served in the KGB.
He is also undoubtedly an extremely effective ruler, his eight year presidency saw restoration of law and stability in Russia, a GDP increase of 72% in PPP (600% in nominal) poverty cut by more than half, average monthly salaries increase from $80 to $640, or by 150% in real rates. He has great popular support.
This is a clever man, who made, and maintains, his position by his own wit & astute strategy.
Numero Uno.