Your favorite black and white film?

Rashōmon
Clerks
On The Waterfront
Frances Ha
Man Bites Dog

might not be my fave B & W but i just watched it the other day... The haunting

Brief Encounter

Agree On The Waterfront was great.

Scream of fear.
Great Hammer story that has been done on other occasions but I've not seen one as intriguing as this version.
... and of course there's the chauffeur's tiny swimming trunks to put a smile/wince on your face 😉

12 Angry Men.

Hello AngularTurnip,
this one just came to my mind -
The Nanny (1965); I think it helped very much to create the weird and dark atmosphere of the whole movie that they made it in black and white instead of, e.g., Technicolor...
Bette Davis impressed me (and William Dix, too! :-)
Kind regards
Andreas (123all4me)

I have more than one favorite black and white film, so here goes:

1) The Beatles' "A Hard Day's Night"

2) On the Waterfront

3) The following Charlie Chaplin Films:

a) The Great Dictator
b) Modern Times
c) Gold Rush

4) Marx Bros. Night at the Opera

5) Arsenic and Old Lace