I've yet to find something that feels wholly satisfactory. The current structure and separation of powers with the US doesn't match simply because of the ease with which it's co-opted by Capital. It edges steadily closer to Feudalism sans titles due to the concentration of wealth and the formation of unofficial-but-functional socio-economic and racial castes.
The consolidation of power seen in authoritarian models inevitably results in rapid corruption but the loss of any meaningful ability to overturn the structure; the state perpetuates itself as the only path to power for the ambitious and dominates the population through military and police coercion and control of resource distribution. And usually toxic propaganda, though that's a problem across the board. In essence, it becomes a monopoly on power maintained by those who
want power.
What I feel is needed is a mixed economic model where there is a private sector, but the most profitable industries within a given State are owned and operated by the same while being bound by business practices standards and regulations. There would likely need to be a set threshold for acquisition by the State based on average profits or stock value of all state companies. The State would rely on the profits of these businesses and a progressive tax model based on income percentages to provide for its citizens basic needs and government functions, with each State paying a percentage of that income to the Federal government to fulfill its functions and assist the States as needed. The government, likely as a cooperation between State and Federal levels, would be responsible for providing the most basic needs of the citizens, but in no way provide luxuries. That would be dependent on individual labor through private or public sector jobs, the former subject to regulation and fair business laws but also protected from the economy of scale available to massive corporations via their inclusion into the government and its own restrictions.
Government itself would need to operate in a system of checks and balances in order to prevent it from becoming too overreaching, too weak, or too corrupt. The US model is fine... except that it needs a great deal more transparency and a higher level of control in the hands of the people. A system for public referendums to override existing laws, determine legislative agendas, and impeach public officials (including Representatives, Senators, Judges, Justices, Cabinet Members, Secretaries, and the President and Vice President) should be put in place. The House and Senate should not vote separately on legislation; they should operate as a single body under normal circumstances and only behave independently in their committees and under peculiar scenarios like traditional impeachment proceedings.
The current lobbying system needs to be completely removed. Gift-giving to politicians creates problems. It's toxic af. Likewise, there should be a prohibition on retiring from politics into the leadership of companies. Stock ownership is fine... However, the entire population of a State should be awarded a set number of shares of each company under State management. Any significant changes in that value will impact the finances of their constituents, and such carry additional political risk for anyone messing around with it inappropriately.
There needs to be a cap placed not only on campaign donations, but on campaign
spending in order to open up the field for the rest of the population besides the current ruling class. This should be coupled with strict limits on how many seats a given political party may hold in either house of Congress, a prohibitive definition of what constitutes a political party that's intended to block the existence of national-scale parties and break up existing ones while also rendering cooperation during campaigns illegal. There should also be full transparency on campaign and other political contributions; Dark Money should not exist. If you're afraid to reveal you're donating to something, you probably don't need to do so. Coupled with the caps on spending, this should reduce the impact of big donors on races outside of flooding races with hordes of candidates from rival parties.
There's honestly more, but I'm getting tired of writing this post