サブクエリを使ってログをカウントし、アクセスが多い上位5件を拾ってくる。

SQL

select (select count(id) from point_logs where point_id = points.id) as log_count, questions.id from questions LEFT JOIN points on questions.point_id = points.id order by log_count desc limit 5;

結果

 log_count | id 
-----------+----
         3 | 18
         3 |  2
         1 | 12
         0 | 11
         0 |  5