Lists and Recommendations : What are the must own movie box sets (dvd or blu ray)?

I own a lot of box sets. The ones I own that I consider must buy: (in alphabetical order)
(I'm limiting my list to just 10)

Alien Anthology blu ray set
Astaire and Rogers complete collection dvd set
Humphrey Bogart essential collection dvd set
James Bond collection blu ray set
The Godfather trilogy blu ray set
Alfred Hitchcock the ultimate collection blu ray set
Stanley Kubrick collection blu ray set
Laurel and Hardy essential collection dvd set
Nightmare on Elm Street collection blu ray set
Star Wars saga blu ray set

Some other sets I own that I really like include: Back to he Future blu ray, Batman blu ray, Frank Capra dvd, Tony Curtis blu ray, Deanna Durbin blu ray, Superman blu ray, Elizabeth Taylor 20 film legacy dvd collection, and John Wayne 20 film legacy dvd collection

What sets do you own? What sets do you consider essential?

I have a Buster Keaton box set and a Peter Greenaway box set. The Buster Keaton one I would consider essential but the Peter Greenaway one isn't great video quality and is incomplete.

That's cool. Buster Keaton is great.

The Exorcist 1,2 and 3 boxset
The Godfather boxset.
Lord of the Rings extended.
Alien Quadrilogy.
A Hammer boxset.

The Chaplin Collection
Harold Lloyd Box set
Val Lewton Box Set

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And This, Too, Shall Pass Away

The Clint Eastwood Spaghetti Western Trilogy.