In most cases, I like movies made in technicolor rather than black and white. But between Pygmalion, directed in 1938 by Anthony Asquith and Leslie Howard, and My Fair Lady, directed in 1964 by George Cukor and based on Alan J. Lerner and Frederick Loewe's 1956 musical play, believe I would pick the former version of George Bernard Shaw's 1913 Pygmalion over the latter each time.
I originally saw My Fair Lady in high school. I thought it was an OK movie. However, after seeing Pygmalion, I just realized that the film makers had taken the same story which My Fair Lady later took three hours to tell and cut it down considerably. Here is the main reason that I think it took Pygmalion a shorter time to make its point: it lacked all the song and dance of the later version.
I liked My Fair Lady when I saw it, but the problem I still have with it is the annoying singsong voice of Audrey Hepburn pronouncing the name of "Henry Higgins" without the H's. Pygmalion was just the story about young, poor girl (Eliza Doolittle) (Wendy Hiller), who is being refined by Higgins (Leslie Howard). It could be looked at as a realistic-fiction movie too. Here is a woman, basically off the streets, who is being tutored by Higgins in a technical way to improve her speech and mannerisms.
Is there any place in such a movie for actors and actresses to break into song? I do not think so. I believe the film makers of My Fair Lady intended to take more out of the realistic fiction role and turn it into a movie for musical entertainment. I guess they could be right on that assumption because Pygmalion had only been made a quarter of a century earlier, and the film makers wanted to film the highly successful Broadway musical instead of remaking the straight play version.
It saddens me to see that Pygmalion is not thought of more as a movie by too many people, while My Fair Lady seems to get legend status. As far as musicals go (and I have not seen many musicals), I guess it was pretty good. But, as far as which one was better, I would take Pygmalion any day of the week, no contest. I would take Pygmalion because it was made for its purpose, just as a basic movie with a basic plot, with no bells and whistles attached.