To answer the thread title question:
Among those movies I've seen there are easily more than hundred movies which I would call a masterpiece, so a list of these would take hours and hours of browsing through imdb (to make sure to remember all of them).
BTW: Movies which I would call masterpieces aren't necessarily those which are my favourite ones (Chaplin's The Gold Rush or Welles' Citizen Kane for example are masterpieces imo, but they are not among my favourites movies).
Instead I just copy and paste my personal top 10 (of the moment) from last week's thread about the same topic:
The Great Dictator
His Girl Friday
Blade Runner
Rear Window
The Band Wagon
Manhattan
La nuit américaine (Day For Night)
Some Like It Hot
The Godfather Part II
One Flew Over the Cuckoo's Nest
