I love watching TCM when I have the time. I watched Gone with the Wind, Diary of Anne Frank, Gandhi and a couple more can't remember titles with Bing Crosby in them.
I watch a lot of old movies. I love romantic ones and comedies. I have watched "Young Frankenstein" so many times and "Arsenic and Old Lace"There are so many others that I love seeing.
Recently watched Casablanca for the first time. Really enjoyed it.
I've got "An Inspector calls" to watch some time (original B&W version) and Gone with the Wind.
Casablanca is comfort food for me and my all time favorite.
Some others that pop in my mind are certain Hitchcock films. I like all of his movies but some I don't find as rewatchable. Gary O' hit the nail on the head for me with the old detective movies, especially the film noir type, and some screwball comedies that have been mentioned plus Bringing Up Baby.
Then there are the old Sherlock Holmes movies with Basil Rathbone and Nigel Bruce. I have watched everyone at least twenty times and will always watch one if it is on. Have no idea why but I love that series of movies by them.
Anything with dancing in it... Shirley Temple, Fred and Ginger, Gene Kelly and Cyd Charisse (oh for legs that look 1/2 that good!), so many great dancers!
I like Bette Davis movies - especially when she's an evil witch - like in "Nanny" & "Whatever Happened to Baby Jane" & "Dead Ringer."
Cagney & Bogart gangster movies are great.
I have an old Mickey Rooney movie with Peter Lorre - "Quicksand." An incredible chain-reaction adventure.
Oh wow, I'm getting old, lol: somebody else called Young Frankenstein an old classic; I abso love YF & think it's a classic but don't think it's old yet, . One I also love watching is Charade, among other things its music: