Which current legislator has served for more terms, Sherrod Brown or Maria Cantwell?
if sum(official_full_name = 'Maria Cantwell') > sum(official_full_name = 'Sherrod Brown') then Maria Cantwell has served for more term than Sherrod Brown; if sum(official_full_name = 'Sherrod Brown') > sum(official_full_name = 'Maria Cantwell'), then Sherrod Brown has served for more terms than Maria Cantwell;
SELECT CASE WHEN SUM(CASE WHEN T1.official_full_name = 'Maria Cantwell' THEN 1 ELSE 0 END) > SUM(CASE WHEN T1.official_full_name = 'Sherrod Brown' THEN 1 ELSE 0 END) THEN 'Maria Cantwell' ELSE 'Sherrod Brown' END FROM current AS T1 INNER JOIN `current-terms` AS T2 ON T1.bioguide_id = T2.bioguide