There's so many interesting metrics. The real cream of the crop metric is which country has the most WR and OR. You could get gold and still be mediocre with mediocre competition relative to the history of the sport, but world record is world record.

The US has a formidable amount of Olympic records even if you account for number of athletes send. And South Korea has an elite crop of athletes. Based on a table I've created from an earlier date, they have the best gold/athlete ratio, and from a quick scan, their number of OR is really impressive. They have half the OR of the US but only have a third of the number of athletes the US has.