@Carpedamnum,
The best type of government for a nation is one that is fundamentally constructed to act, only, in the best interests of the governed; within a framework that balances maxium accountability and minimum instability. A representative democracy, it seems to me, best fits the bill.
It is also one in which power is dispersed in such a way that it is difficult for centralized government to make significant and long term changes to the way of life of the individuals governed, and yet rapidly efficient in responding to limited and well defined emergencies. Dual federalism, in my opinion, best fits this bill.
Assuming that I will never receive a mandate to rule as a dictator or be allowed the sole discretion in selecting one, the government that is best for the nation (described above) is the best for me individually.
I'm not sure what you mean by "best for politics," but whatever form of government requires the greatest number of parties to enable it to act is the one most heavily dependent upon politics.
Given the power sufficent to remake the current government, I would not squander it on trivialities like accountability, representation, or politics. I would immediately get to the job of making everything good and right as the first and most benign American dictator.
Actually, there are really no fundamental changes I would make to the exisiting form of the US government, although some of the changes I would make (like reducing the scope and size of the federal government) would no doubt be perceived as extreme or radical by certain others.