Almost impossible to choose, but Vertigo is my all-time favorite film, due in no small part to the masterpiece, endlessly fascinating Herrmann score.
Funny enough, while it was raining this morning I decided to pile up on the couch and watch something "fun" for a rainy day, so I chose "Family Plot." Having only seen it on smaller TVs since originally seeing it in a theater back in '76, it was really a treat with my now-huge tv and rich surround sound. I love the Williams score (and CD!!!) but I hadn't watched the film itself in a long time. Amazing how the years have been kind to this movie once you get past the bad process work and William Devane's 'stache.
Anyhow, hearing the terrifically spotted score WITH the film for the first time in ages, I'm just in awe of what an all-around treat and marvel JW's score is. (It helps that Jaws-thru-ET is my favorite Williams period), and the score is drenched with that marvelous CE3K/Fury-era business. From the haunting and gorgeous Séance theme, the cleverly interpolated love theme, well-used suspense and electronics, little Herrmanneque pastiches and of course a wonderful main theme, I was sitting there thinking "when has this man ever NOT been firing on all cylinders?"
So even though it's not my top favorite of all Hitchcock scores, just had to shout out for it. I was actually weighing Family Plot's score among all the Hitch music today, so the coincidence of your post was almost eerie!
For me, Hitchcock was graced with the two best scores ever written for film - "Psycho" and "Vertigo". Once he severed his relationship with "Benny" and his films flopped he began to understand the nature of their symbiotic relationship and the importance of his music to the success of his films. Too late.
I would say that NORTH BY NORTHWEST is my favorite Hitchcock score, but I think MARNIE is in some ways more accomplished. The music grabs hold of you the instant the main title begins and doesn't let up. In so doing, the score makes the film seem much better than it is.