For the very best of existential arthouse, you cannot beat films of the French New Wave, particularly those made by Jacques Rivette. I highly recommend the following:

La Belle Noiseuse (1991).

Jacques Rivette's award winning masterpiece is an adaptation of Honoré de Balzac's Le Chef d'oeuvre inconnu, and can be read in part as an apologia for the narrative cautiousness that his work has shown, since the dangerous experimentation of the equally stunning and magnificent L'Amour Fou in 1968.

Brutal. Yet paradoxically, not brutal at all.