James Cagney in the play Maggie the Magnificent, 1929.
Lady Killer (1933)
Say, this racket’s the bunk, isn’t it? Three bucks a day and a boxed lunch that would kill a horse!
Here’s the boy who has been knocking ‘em cold at the box office.
The New Movie Magazine, 1932.
Glenda Farrell and James Cagney attend a barbecue, 1935
NOIRVEMBER DAY 10 - White Heat (1949) dir. Raoul Walsh
The Public Enemy 
Speaking for myself, I got into Cagney the summer of 2009 as I was reading the book Public Enemies by Bryan Burrough (also the movie was coming out and I’m obsessed with that time period in crime) and in the book they mention James Cagney and his “gangster films” and I found out that he made a movie called The Public Enemy and decided to check it out so I purchased the Warner Gangster Collection on a whim with The Public Enemy, The Roaring Twenties, Angels with Dirty Faces, White Heat etc. and instantaneously fell in love with the man’s talent and charm and everything.
As far as my favorite films — I LOVE EVERYTHING!!! But if I must narrow it down I would say just in terms of how many times I have watched it — it’s a tie between Picture Snatcher and Blonde Crazy :)
Now that you mention it I do see a little bit of resemblance in the face but only for a young James Cagney pre 1934. That’s really weird lol.
James Cagney takes a bath in Picture Snatcher (1933)