I belong to a different generation and my favourite movies may be quite different from yours.
When I turned 6, I was able to make little sense of the conversations in movies. Thereafter, my uncle and aunt made me and my cousins watch a lot of good movies. Of the ones I saw, I recommend:
(a) The Sound of Music: Its a true story of the Von Trapp family and the Captain's seven children and the nanny (Maria) who later goes on to become the children's step mother. The songs, specifically, are amazing!
(b) Chitty Chitty Bang Bang: Yet another musical, but its a great creative story of a car that also flies. Well, its actually a story inside a story which has been directed really well.
(c) Mary Poppins: It stars Julie Andrews (aka Maria of The Sound of Music) and it became a favourite by default. Point to note: It's supercaliflagilisticexpialidocious :)
Here's is The Telegraph's top 20.