My familiarity with pre-1950 movies is limited; my preferred period is 1950-to the mid-1970's. The pre-50's flicks that made an impression on me are listed below. I included in most cases the director and the stars along with the date of release. At my age my memory has a lot of gaps, so I had to look up most of the dates -- in part to verify that they were released before 1950 -- as well as directors, and actors in The American Cinema or Wikipedia.
Way Down East (D.W. Griffith, starring [the ethereal] Lillian Gish & Richard Barthelmess, 1920) Sort of a Thomas Hardy type story as a silent film.
Steamboat Bill, Jr. (Buster Keaton, 1927). The one where buildings keep collapsing on Buster.
Shanghai Express (Joseph von Sternberg, starring Marlene Dietrich 1932) Because it's visually outstanding.
Roberta (William Seiter, starring Astaire/Rogers & Irene Dunne, 1935) Ginger singing Hard to Handle with a weird Russian accent is my favorite bit.
Libeled Lady (Jack Conway, starring Jean Harlow, Myrna Loy & Spencer Tracy, 1936) The stars drive this screwball comedy.
The Awful Truth (Leo McCarey, starring Cary Grant & Irene Dunne, 1937)
Grand Illusion (Jean Renoir, starring Jean Gabin, Erich von Stroheim, & Pierre Fresnay, 1937)
Swing Time (George Stevens, starring Fred Astaire & Ginger Rogers, 1937) The first number with Ginger Rogers in a black dress (the movie is b/w so maybe it's just supposed to be dark) and high heels versus Fred Astaire is really something. It was my introduction to the Astaire/Rogers series.
Rules of the Game (Jean Renoir (who also has a major role), 1939) Saw this again recently; it gets deeper every time I see it. Upper class hunting party on the eve of the war, not knowing their world is about to collapse. Renoir didn't foresee that eventually inequality would be restored big time in the next century.
The Wizard of Oz (Victor Fleming; George Cukor did some work on this, but Fleming gets director's credits; starring Judy Garland, 1939) Saw this in the early 50's when I was a child and hadn't seen many color movies, if any, so the door opening into Oz was a big deal. Also, the witch terrified me.
The Women (George Cukor, starring Joan Crawford, Rosalind Russell, & Norma Shearer 1939) All female ensemble, like women's bball. Based on a stage play by Clare Boothe, who later married Henry Luce of Time and Life (ask grandpa about these influential print publications) Not really a big fan of Gone with the Wind.
The Shop Around the Corner (Ernst Lubitsch, starring Jimmy Stewart & Margaret Sullavan 1940) Another good one is To Be or Not to Be, but this one is so sweet.
The Lady Eve (Preston Sturgess, starring Barbara Stanwyck and Henry Fonda, 1941) Stanwyck always seems to light up a movie, and she made plenty of them; they often surface on TCM. She seems to have consistently played sharp, intelligent women in all of them. Probably my favorite actor from this period (which included Hepburn and Myrna Loy).
Day of Wrath (Carl Dreyer, 1943) About witch hunting in 17th century (?) Denmark -- with Europe under the Nazis as an underlying theme. The scariest part is how the stress of the persecution culture sucks people into the dark side.
The Big Sleep (Howard Hawks, starring Humphrey Bogart and Lauren Bacall, 1946) A film noir based on a Raymond Chandler detective novel; William Faulkner worked on the script; since it's about a crazy double-dealing family, you can guess the attraction.
Letter from an Unknown Woman (Max Ophuls, starring Joan Fontaine & Louis Jourdan, 1949) A really dark film. I believe Caught with James Mason is also from this period. Ophuls' movies from the early 50's are OT, but if you haven't seen them, they're really good: La Ronde, Le Plaisir, Earrings of Madame de ...
I left off Bringing Up Baby because I've only seen it once, and quite recently. It was excellent, though.
