Any type of oligarchy falls under my understanding of dystopic by definition. Allowing a very small minority to govern over the remaining vast majority has been proved to be unsustainable. The individuals taking part in an oligarchic government are usually very different from the population they control. In noocracy is the wise, and in kraterocracy is the strong, but there is always a differentiation between the few and the many. This type of government can therefore be easily (ab)used to serve the needs of the few without addressing the needs of the population.
Similar to oligarchies, autocracies, including monarchies, serve the sole purpose of fulfilling an individual’s desires and needs. Referring to Eco’s Ur-Fascism and the vicissitudes of the 20th century it is clear that this is also an extremely detrimental and unsustainable type of government not only for the local population, but also for the wide global stability.
I believe that, on a theoretical level, there has to be democracy for it to be justice. Liberal and social democracies may be the two of the most commonly diffused forms of democracy, but they are both indirect democracies. Their indirect form can often lead individuals to feel like they do not actually have control over the decisions being made because modern day politics has developed to be a place where economical alliances are worth more than the principles guiding a political party. For this reason I would adopt a direct democracy so to make voting an actually impactful action. However, I would make sure that a constitution of some sort is in place to safeguard the rights of the overall population.
A republic is also a viable option to make sure that the well-being of the population is the priority of a government. Of the types of republics, the preferable one would be the constitutional one for the reason mentioned above. A democratic republic still seems like a danger to human rights considering it solely depends on the majority, and a presidential republic sounds like an autocracy masked as republic.
At last, a democratic republic seems to be the right mix of the two options of government that, at least on paper, have at heart the rights of the overall population.