The best type of government is natural...

It's the one already inside of us: Federal Republic

All of your organs are autonomous but act under the brain
It's a healthy mix of centralization and decentralization.

Also it wouldn't be a Confederacy because that would imply voluntary unification. The things that make up your body are forced to act together as a single unit.

>>2
Also it wouldn't be a Confederacy because that would imply voluntary unification.
While true that it was a voluntary unification, it's not true that it would be voluntary for states to leave the Union once in during the first American Confederacy. If you read the Articles of Confederation, it says somewhere that the Union shall be perpetual; that hasn't changed since the current constitution came into effect.

>>3
confederacy in definition, not USA confederacy

kind of like,
liberal in definition, not USA liberal

>>4
confederacy in definition, not USA confederacy
It depends entirely on the stipulations of the contract. There's no error in definition. For example, the republics of the Soviet Union broke away, and the 1977 Soviet Constitution allowed for individual republics to leave that union if they so wished. And that's exactly what they did.