Pygmalion , directed by Anthony Asquith and Leslie Howard in 1938, and My Fair Lady, directed by George Cukor in 1964, both based on George Bernard Shaw's 1913 Pygmalion, are both excellent movies that I enjoyed very much. But I would have to say that I enjoyed My Fair Lady quite a bit more.
Another major factor in my favoring My Fair Lady is simply the fact that I am an avid fan of musicals. I find witty singing to be very entertaining. I think many people dislike musicals because they require that the listener pay a lot of attention to the words of the songs. But if one pays attention to the words, then one oftentimes finds great wit and humor in them. I found the songs in My Fair Lady to be excellent. My personal favorite was "Get Me to the Church on Time," sung by Stanley Holloway as Alfred P. Doolittle, which was funny but which never took place at all in Pygmalion.
My favorite character in both movies was Alfred Doolittle. He was always an upbeat and entertaining character. In some ways he is my role model. If I have that much energy and fun when I get to later adulthood, then I will have lived a full life. I was fonder of the My Fair Lady version of Alfred mainly because he is made out to be a larger character in that film; he gets two songs and has plenty of screen time. On the contrary, in Pygmalion, one does not see Wilfred Lawson's Doolittle very much, so he makes much less of an impact.
The leading men, Leslie Howard in Pygmalion and Rex Harrison in My Fair Lady, were both very good as well. Both seemed to carry an air of pretentiousness that an aristocratic upper-class person of that time would have had. Personally, I was more partial to Rex Harrison's portrayal of Henry Higgins. In Pygmalion, the audience really grows to dislike Henry Higgins as he is portrayed with very few redeeming qualities and never really seems to care. In My Fair Lady, he is shown a few times to be human. A good example of this is the night when they are playing the music and dancing around the room after Eliza finally said, "The Rain in Spain" correctly. This did not take place in Pygmalion. I feel that this was done so that the audience would be more inclined to want Professor Higgins and Eliza to get together in the end.
Both films were entertaining although, if I were asked to recommend one to a friend, I would most definitely choose My Fair Lady. The characters were generally better and the music was great.