I like some of these, and some of these aren't musicals, but none are my favorite, for which there is no option but "None of these/no opinion, which, *ahem* *ahem* taptaptaptap isthisthingon ARE NOT SYNONYMOUS!!!!!!!!!!!!!
Whew. All better now.
My favorite is Singin' in the Rain, which fits all requirements of the poll:
1. It is a movie, not a stage production.
2. It is a musical, where characters burst into song based on the emotion and actions of a scene, which song's lyrics serve to further the plot, theme, and story.
3. It is a movie musical that was created and exists only as a movie,* not as another format adapted for the screen.
Let us examine the nominees:
The Blues Brothers— the songs are not original, and do not reflect anyone's emotions or the plot or action of a scene. Therefore, not a musical. Should have been stripped from the poll.
Fiddler on the Roof— written for stage and adapted to film later. I'll allow it, but SitR is better anyway. (Plus, Fiddler plagued the world with "Sunrise, Sunset" which is hard to forgive.)
The Sound of Music— written for stage and adapted to film later. I'll allow it, but again SitR is better and a lot more fun. (And less sappy, to be honest.)
West Side Story— written for stage and adapted to film later. So allowed, but still not anywhere near as enjoyable as SitR. A stage production is almost always superior to the film. Plus modern-day remakes of Romeo & Juliet to me are a bit thin on originality. Still, this was probably the first; it's certainly the best (low bar, but it clears it handsomely). But after a while the whole Sharks/Jets thing becomes hokier and less believable. Those aren't street gangs. The Warriors would shred ‘em both in less than a minute. Stage, fine. Movie… your stylist is showing.
The Wizard of Oz— Finally, an actual movie musical on the list. Written for film, the songs reflect the characters' feelings and actions, and a darn good movie. And there's nothing sappy in the mix. I'd probably rank this second after SitR. But since it is not my favorite, "None of these" must be my choice.
*The plot of Singin' is about creating a full-length "talkie" movie musical in the era of silent film, and thus relies on the function of film itself as inherent to the plot, theme, and story. It has been adapted for the stage, but it wasn't written that way, and to me putting it on stage misses the whole point.