If by 'clever and engaging' you don't set the bar as high as (to name a few examples) The Usual Suspects, Fight Club, Saw I & II type 'clever and engaging', I think that at least the following in the top 10 would fit the bill (and rightly so):
(1) Titanic
(2) The Dark Knight
(3) Star Wars
(5) ET
(8) Spider-Man
The top 20 list however, is far from based on good taste, with movies like Dead Man's Chest, Spider-Man 3, Kingdom of the Crystal and At World's End and ermmm..... Revenge of the Fallen, in it.