How can we konfirmasi that Bambi was actually Walt Disney’s favorit disney film as berkata oleh 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 berkata that they 'believe' that it was was his favorite, but that's not knowing for sure. Otherwise, they would've berkata that it's his favorit rather than adding "believe" with it.
I do know that Diane(his only biological daughter) is berkata that her favorit movie was Fantasia as I heard she even attended a I think it was 70th anniversary of Fantasia.
Any proof anda have on her father's favorit film though?