Does NZ have the best designed Government in the world?

Dylan Matthews at Vox argues NZ has the best designed Government in the world. He cites three things which are crucial:

1. NZ’s MMP system which delivers proportional results but also retains electorate seats
2. NZ’s Unicameral Parliament with no Upper House. He argues Upper Houses tend to be useless and undemocratic.
3. NZ’s Constitutional Monarchy which provides a Head of State with no legitimacy to interfere in domestic politics

I’d don’t agree with all his arguments but he makes a good case. I’d add a 4th. No state parliaments. No disputes over what is the role of central government and state governments, and no duplication of multiple police forces, education ministries etc.