The fairest system would be a flat tax per person, surely. Each person will use a pretty average amount of state resources. It's expensive to live in California, after all.
It wouldn't surprise me, though I've usually seen that applied as a reductio ad absurdum to show that the notion of a flat percentage as "fair" is arbitrary because surely a flat tax would be even fairer - on the basis that it highlights how flattening out the tax curve can make the burden on the poorest unsustainable.