What is the most common type of compliments that a user has received from other users?
the most common type of compliments refers to MAX(COUNT(compliment_type))
SELECT T2.compliment_type FROM Users_Compliments AS T1 INNER JOIN Compliments AS T2 ON T1.compliment_id = T2.compliment_id GROUP BY T2.compliment_type ORDER BY COUNT(T2.compliment_type) DESC LIMIT 1