Which Blurays would you buy just for completist's sake?

[filmmusic]

I am not sure if I put it right in the title (since English is not my native language).
This thread is about movies (maybe not just specific movies but groups of movies - by director, genre, actor, studio, etc.), that you could do without in Bluray or it's not on top of your priority of the movies you love, but you would like to buy nonetheless just to complete a collection of something..

eg.
-I would like to buy all Hitchcock blurays. (that doesn't mean that I love all of them, or I can't do without some of them)
-also I'd like to buy complete filmographies (if they were released in Bluray) of certain actors like Cary Grant, Elizabeth Taylor, Rock Hudson, Marlon Brando, Katherine Hepburn, Judy Garland, Fred Astaire etc..
-all the 2d Disney theatrically released animation films