I would favour a fixed amount in a fairly large geographical area. Areas that are expensive to live in also have a need for jobs like cleaning the streets. If

I would favour a fixed amount in a fairly large geographical area. Areas that are expensive to live in also have a need for jobs like cleaning the streets. If people have the choice of living somewhere cheap on UBI then the pay for lower skilled jobs in these expensive areas will have to rise to get people to take them. I would expect the cost of this to have to come from higher property taxes in these more expensive areas which could act to bring down the difference in costs between the different areas.