United Kingdom (1960–1968) against United Kingdom (1965–1973)
Jackie Stewart wins this one without much argument: more titles (3 against 2) and a clearer edge in dominance once scaled against their competition, averaging 38% of the maximum possible points per season against 32% for Jim Clark. On every other measure though, it's Jim Clark who comes out on top: win rate (34.2% against 27.3%), podium rate (43.8% against 43.4%), pole rate (45.2% against 17.2%), and reliability (38.4% against 38.4% in DNFs). The two never raced for the same team, so never went head-to-head in identical machinery. The full interactive comparison (link below) remains the fairest way to bring them together despite the era gap.