

Any country larger than ~100k km^2 - simply because even at that side there are vast cultural and economic differences that require different governing styles, and have different attitudes to certain topics.
With smaller countries come smaller, more localised decision making that benefits the most people of the region, and thanks to being small, it puts emphasis on these smaller states working together instead of being antagonists of their neighbours.
Oh and it also solves the issue of a small percentage of the population electing a complete buffoon with unfettered access to nuclear launch codes.
Hell, bring that 100k down to 20k and it’s still a manageable system that better represents 80+% of the population than a large government of a large country.
Can we please burn Palantir to the ground already?