Democracy. Everyone deserves a democracy, self-determination, the right to secede democratically from a larger polity, and the right to form countries as small as Liechtenstein or smaller. Complex borders are not an issue (see this example https://en.wikipedia.org/wiki/Baarle-Nassau) https://medium.com/non-violence/stakeholder-control-avoiding-war-thru-flexible-democratic-boundary-shifting-bf6f9c20e578