DonM Using those percentages, the five-footer has the best return, then the ten-footer, then the three-footer, then the 20-footer.
Problem is that those are tour averages. Amateur make percentages are not only lower across the board, but it is highly likely that the difference in percentage made goes down a steeper slope for amateur golfers. In other words, the difference between the percentage we make at three feet and five feet is larger than that of the pros, and moving to ten feet it would likely slope off even more.
For the amateur, the five footer may still be the right answer, but I wonder if the three footer and the ten footer might be pretty close to the same. More concretely, if the amateur makes 20% of his ten foot putts instead of the nearly 30% of the tour pro, the three footer and the ten footer become equivalent.