Breaking my favorite films down by decade makes it a bit easier to rank them. For about 6 years (since I got into the classics), the 1940's top 2 films---Now, Voyager and Casablanca---took turns as my all-time favorite movie. However, since September, 2012, my favorite film of the 1950's---A Place in the Sun---has taken the #1 place, toppling Now, Voyager and Casablanca to the #2 and #3 positions. Of course, it is entirely possible that either of those movies will regain #1 status; also, as I discover new movies, this list will see some changes, but as of January, 2014, this is how everything shakes out.
1930's
1. Mr. Deeds Goes to Town
2. A Star Is Born
3. Make Way for Tomorrow
4. Imitation of Life
5. Stella Dallas
6. It Happened One Night
7. Dark Victory
8. The Public Enemy
9. Angels with Dirty Faces
10. Gone with the Wind
1940's
1. Now, Voyager
2. Casablanca
3. The Best Years of Our Lives
4. Penny Serenade
5. I'll Be Seeing You
6. Random Harvest
7. Tomorrow Is Forever
8. Humoresque
9. The Postman Always Rings Twice
10. Pride of the Yankees
1950's
1. A Place in the Sun
2. Sunset Boulevard
3. Stalag 17
4. Roman Holiday
5. An Affair to Remember
6. Sabrina
7. Born Yesterday
8. Pillow Talk
9. Ten North Frederick
10. Middle of the Night
1960's and beyond
1. Madame X
2. Les Miserables (1970's)
3. The Sound of Music
4. To Sir, with Love
5. Strangers When We Meet
6. Shenandoah
7. That Funny Feeling
