That still a pretty big and vague thing to say though, I mean it could mean anything from a special ability/tech for a civ, to something applied to one or more buildings, to something depending on territory, to something else I guess. I personally don't have much of an opinion for or against either of them, though I'd say I*d prefer something linked to e.g. houses or some specific building over something more general/tied to territory. That way you would have to spend something for each increase in income, and for that matter can be more strategic about e.g. where you build your houses. If it's just territory it feels as if players would be encouraged to spend a lot of time putting their buildings just the right distance from each other so they'd get the maximum territory. And that doesn't sound interesting at all, having a reason to careful with the houses, and value them more, could certainly be interesting though