How can we confirmer that Bambi was actually Walt Disney’s favori Disney film as a dit par some people?(read description)

Well that's what I hear, but where exactly is the proof though? I haven't found any biography based stuff like if Walt ever personally mentioned it was his 'favorite'. The only thing I've found is in a Making of Bambi video where two of creators a dit that they 'believe' that it was was his favorite, but that's not knowing for sure. Otherwise, they would've a dit that it's his favori rather than adding "believe" with it.
I do know that Diane(his only biological daughter) is a dit that her favori movie was Fantasia as I heard she even attended a I think it was 70th anniversary of Fantasia.
Any proof toi have on her father's favori film though?