I'd aim for social justice first and foremost and economic prosperity as by next big aim. Generally the role of government is the latter more so than the former, but I would attempt to rectify this. Of course, that isn't to say that economic policy wouldn't be of great importance. It would. Social justice can be largely achieved through economic policy. But economic prosperity would come as a secondary aim behind this, where reasonable. I'd take greater control of the economy, but retain the market economic structure, aiming to reduce market failure as much as possible.
I'd make sure freedoms were preserved, and I would attempt improve the education and health systems as major priorities. Oh, and my foreign policy would be largely individualistic, with a focus on human rights more than geopolitics. Foreign aid would drastically rise.
But if I were any of the politicians mentioned in the OP, these aims would probably be distorted by various real world situations.
If I were Putin, I would aim for more transparency in government, and more cordial relations with western neighbours. I would probably free up the economy a bit more, whilst maintaining a reasonable distribution of income and wealth, before taking back more control once the economy had improved to a more reasonable position. I would widen the export base, focusing on a services based economy. Education would be a key policy, also, to improve economic prosperity.
Hu? More individual freedoms, obviously, and a greater focus on individuals in the economy, over businesses. This could be detrimental to the economy to a degree, but an improvement in the working conditions/pay conditions of workers would be beneficial in the long run. Foreign policy would slowly move towards my own end goal, and I would obviously stop repression within China, but in the meantime I would continue to be wary of, at least appear to be wary of, America. It seems to make sense.
Obama would be tricky, because I can't really think of anything I would do particularly different, other than go further to the left, and expand upon his policies more so. Health care would be a priority, but I would be more 'radical' about it, fiscal policy would be similarly expansionary, etc. Foreign policy would be made more human rights focused, and less focused on the traditional Israeli platform. I would continue to be open to Iran, NK and Russia, and hope they respond accordingly. Other than that, there aren't really any major things I would do differently (other than completely reform the American education system- it seems to be pretty horrible), but there would be plenty of small differences. And that doesn't mean I'm an Obamaphile.
Khamenei- I would open the nation up more, perhaps abandon the nuclear program (despite my perceived right to actually have it; other nations are just not understanding enough for it to work), sack Ahmadinejad, improve relations drastically with America and Israel, and improve individual freedoms, beginning with the removal of Islamic Law. It's a bit hard to correspond to realistic Iranian behaviour, because I just wouldn't continue Islamic Law.
If I was Chavez, I think I would continue following a reasonably socialist path, in line with my own aforementioned economic policy, and I would be wary of moving too quickly, to avoid the ire of other nations. I would continue with warm relations with Russia, but I would also attempt to be conciliatory towards America.'
Merkel- invade Poland I don't know about too many German specifics, but I think I would just follow my general policy outlined above, perhaps with less socialistic economics, for fear of becoming the opposition.
