What is the biggest amount of reviews a salable product gets?
salable product refers to FinishedGoodsFlag = 1; biggest amount reviews refers to MAX(count(ProductID))
SELECT T1.Comments FROM ProductReview AS T1 INNER JOIN Product AS T2 ON T1.ProductID = T2.ProductID WHERE T2.FinishedGoodsFlag = 1 GROUP BY T1.Comments ORDER BY COUNT(T1.ProductReviewID) DESC LIMIT 1