This 1950 James Stewart film Harvey is my ultimate feel good film. The protagonist is just so inspiringly polite and gracious throughout the film that it is impossible to watch it without actually becoming a slightly nicer person.

It is a hard film to explain to anyone else (this is the voice of experience) because I don’t think the idea necessarily works on paper. (Although it worked perfectly fine on the stage. It was a Pulitzer Prize winning play before it was a film.) Jimmy Stewart plays Elwood P. Dowd whose best friend is a six foot tall rabbit called Harvey who only he can see. This causes his sister to have him committed to a mental institution. It sounds like One Flew Over the Cuckoo’s Nest meets Watership Down meets Drop Dead Fred.  It is like The Princess Bride though, you just have to see it to get it.
The main reason for the film’s incredible charm is its leading actor. James Stewart is one of those actors who is always immensely endearing and here he is at his most James Stewarty. If you are familiar with the man then that should be sufficient reason to watch this film but if not then you should stop reading this immediately and go and watch The Philadelphia Story, The Man Who Shot Liberty Valance and Vertigo. 
That isn’t to say that James Stewart provides the only watchable performance. Josephine Hull as the sister is a little histrionic but the film is full of those deliciously one dimensional characters that populated mainstream cinema at the time. The upright young nurse, the crotchety old family lawyer, the comedy drunk, the down to earth working class heavy with a heart and the sceptical old doctor. They are all here making you hanker for a time that never really existed.
Like most film fans I find it impossible to name one favourite movie but Harvey would always be in the top four. It also includes what is (probably, possibly, maybe) my favourite piece of screen dialogue. I’m going to heinously misquote it but hopefully you’ll get the idea.
“Did I ever tell about how I met Harvey? I heard a voice say ‘Good Morning Elwood’. I turned around and standing there was a six foot white rabbit. I was a little taken aback at first but then I realised that when you’ve lived in a town as long as I have everyone knows your name.”