Who wins?
Calling Uno on someone vs Saying "Uno"
Saying "Uno" wins 53% to 47%. 118 more put them in the same row. From Board Game Rule Debates Tier List. Pick a side.
soggy_frog on Calling Uno on someone: catch them before the next player goes and they draw two
RandomPossum on Saying "Uno": it's printed in the rules, two card penalty if you forget
Board Game Rule Debates Tier List: the full ranking