I made an advanced search on IMDb and found that there are eighteen feature films with more than 200 votes released 1920. I have seen eleven of those, the rest of them don't sound as if they are going to interest me enough to enter this list.
What's great about old films is that many of them are legally available online for free at archive.org, youtube for example. I will make a link to where you can watch each of these five movies.
Top 5 Movies Released 1920
Nr 1: Way Down East (1920)Directed By: D.W. Griffith
Genre: Drama, Romance
Nr 2: Prästänkan (1920)Aka. The Parson's Widow
Directed by: Carl Theodor Dreyer
Genre: Drama, Comedy
Nr 3: Why Change Your Wife? (1920)Directed By: Cecil B. DeMille
Nr 4: Das Cabinet des Dr. Caligari. (1920)Aka. The Cabinet of Dr. Caligari
Directed By: Robert Wiene
Nr 5: The Penalty (1920)Directed By: Wallace Worsley
Genre: Crime, Horror, Drama
Way Down East is a film about a girl's loss of innocence. The main character, Anna Moore (Lillian Gish) is tricked into a sham marriage by a womanizer, who leaves her alone and pregnant. Having a child without a husband was considered shameful those days and the girl struggles to keep it a secret when she starts working on a farm. This is also a film about the inequality between men and women and I'm sorry to say that some of the probems this film deals with hasn't changed much.
Prästänkan: A young man and his girlfriend arrives in a small Scandinavian village, where the man applies for the post as new parson of the village. He gets the job but there is one problem - he has to marry the widow of the former parson. The young parson and his girlfriend has to pretend that she is his sister so that she's allowed to live there.
Why Change Your Wife? is a comedy about a relatively young man who divorces his boring and too mature, young wife played by Gloria Swanson. He marries another young woman, but quickly finds her to be too childish. On a vacation they happen to visit the same hotel as the ex-wife, who has changed and no longer behave like an old lady. This might be the first silent comedy I've seen that's not slapstick, and it was actually great. Romantic comedies hasn't changed much, they were only better before.
Das Cabinet des Dr. Caligari. is one of the most well-known silent movies today, with over 20000 votes on IMDb. It's about a man telling a horrifying story about a killer somnambulist (a word I thought sounded cool but didn't know what it was, so I had to ask google translate). What I like most about this film is the amazing style of the set construction. This is also known as the first movie with a twist ending.
The Penalty is a crime movie starring one of the biggest stars of the 20s, Lon Chaney. He is a criminal mastermind in San Fransisco who plans to take revenge on a doctor, who mistakenly amputated his legs when he was young.