Which state has the highest number of clients who gave a 5-star review?
highest number of clients refers to MAX(COUNT(client_id)); 5-star review refers to stars = 5;
SELECT T2.state_abbrev FROM reviews AS T1 INNER JOIN district AS T2 ON T1.district_id = T2.district_id WHERE T1.Stars = 5 GROUP BY T2.state_abbrev ORDER BY COUNT(T2.state_abbrev) DESC LIMIT 1