So the hardest part about any model of governance is that so often planning for "good governance" is not just about governmental structure, it's about competition and the composition of the people involved in that competition. Perhaps understanding the benefits and drawbacks of different types of government doesn't matter as much as understanding the culture/environment in which and through which a particular organization operates. You have to weigh internal personalities and external factors and plan from there. It's all so humanly variable.
This is, in short, to say that there's no "one size fits all" approach to government. I'm sure I'm not saying anything unexpected there, but the age-old debate of democracy vs. oligarchic technocracy vs. autocracy will rage on forever because it ultimately comes down to the net competency of particular sets of individuals living in a particular place and time. That's true across each of the public, private, and voluntary sectors. I'd say experimentation is key.
Try these specific Wikipedia series if you're looking to deep dive into the topics you're asking about:
(Governance) (Electoral Systems) (Forms of Government)
I'd also like to point out that there is a slight distinction between government and governance. The former generally refers to the structure and the latter generally refers to the process.
I like the idea and the rationale. I'll admit I rarely put much stock in quantifications of the future (let alone quantifications crowdsourced by an audience whose qualifications cannot be ascertained). But, I think it would be fascinating to reflect back to this clock come 2028 and if AGI has not been agreeably achieved by then to ask ourselves "Well, how far have we come and how much longer do we suppose it will take?".
What I don't understand is why you're convinced that the introduction of AGI will result in you personally becoming transhuman.