Bunuel was a surrealist in the 20’s, made films in Mexico in the 1940s and 1950s, made one film in his native Spain in the 1960s which was banned there and finally made films in Europe (mostly in French) with prominent actors.
I would start with Nazarin (1959), Viridiana (1961) The Exterminating Angel (1962) and Tristana (1970), three of his more accessible films.
Then I would move on to The Milky Way (1969), The Discreet Charm of the Bourgeoisie (1972), and The Phantom of Liberty (1974).
What a great career. Bunuel had a wicked sense of humor. I remember the cross that folded out into a knife in The Exterminating Angel
I have watched some of his lesser-known Mexican films and recommend El (1953) and The Criminal Life of Archibaldo de la Cruz (1955).
BFI on where to begin with Bunuel
El has never been issued on any US DVD or Blu-ray.