8½ (1963)
I agree.
I hope a lot of people chime in. I'll propose La Strada.
La Strada is excellent. It is my 2nd favourite Fellini film.
how about Roma?
La Dolce Vita is a timeless classic and can be watched throughout a lifetime, as Roger Ebert said, you see something challenging or new in it every time, as you age.
Close call but I'd go with 8½ narrowly over Nights of Cabiria.