The "Most successful Swiss soccer club" is highly debatable.
To this day, Grasshopper is still the one that has the most Swiss championships and Swiss cups won, and by a substantial margin (7 more championships than FC Basel and 6 cups more than FC Basel, which is second in both rankings).
To this day, Grasshopper is still the one that has the most Swiss championships and Swiss cups won, and by a substantial margin (7 more championships than FC Basel and 6 cups more than FC Basel, which is second in both rankings).