Sorry for my very late answer John.
I will hopefully write more about the films I listed and maybe add some others when I have more time.
For now let me just say, that by Straub/Huillet, I think "Class Relations" (1984) is a must. An adaptation of Kafka's Amerika in german the film is imo one of the greatest films in cinema history. I've written a lengthy review of it, but as it's in german, and I don't have the time or nerve to translate it, I hope you will just believe me Or maybe you can find something on it in the net.
Othon is of a different quality, and one which I would think much more accessible, but obviously I was wrong in my judgment. Nevertheless the two critics listing it as the "worst film" must have skipped the film, as this is a very very stupid assessment. Maybe more excusable if they are not used to the french language but even then The film is a very static "enactment" of a phenomenal french play of which I have unfortunately forgotten title and author. It may not be one of the greatest films ever, but in it's use of language it may be one of the most pleasurable films imaginable. The beautiful text recited in the context of this film - presented through the powerful cinematography of Renato Berta -Straub/Huillet's structuring brings about a tremendous sensual pleasure as well as bringing its meaning to the surface.
If you speak french, a must!!