Personally, my initial interest in Bergman was never very fervent, and I admit I feel mostly ambivalent about him today—but I also enjoy returning to his work, particularly the later stuff. Without disparaging the 50s favorites that made him perhaps the foremost cult figure of art cinema pre-French New Wave (in the United States, at least), I think the best way to approach him is through his 60s and 70s films, where he left behind empty aesthetic showboating and made more serious and worthwhile attempts to explore mankind's crisis of belief, particularly as it pertained to modern art and modernity in general. In any case, you can find my five favorite Bergman films below.
5. Sawdust and Tinsel (1953) Probably the highlight of Bergman's early phase, this stark tragicomedy, the expressionist inverse of Summer with Monika's realism, has a masochistic edge, but it's also among the director's most beautiful films, filled with lush chiaroscuro and an ambitious closing sequence.
4. Shame (1968) A war film that's not actually about war. Bergman is more concerned with war's inevitable absorption of people and the way it exposes hidden and unappealing features in the human subject. The subjects in question are two naive concert violinists, and their tragic transformation, spurred by a set of increasingly blurred and compromised ideologies, brings profound meaning to the term "identity politics."
3. Autumn Sonata (1978) As Dave Kehr notes, Bergman is working in miniature with this chamber drama, but the results are nevertheless massive. Ingrid Bergman and Liv Ullmann play an embittered mother and daughter, and their respective hang-ups and acrimony toward each other not only reveals painful truths about human emotion and the nuclear family, but illustrate the filmmaker's remarkable direction of actors.
2. Wild Strawberries (1957) One of Bergman's most moving films, nostalgic and sentimental but never cloying or irritating. The director's idol Victor Sjöström plays the lead role, and there are shades of his own directorial style in the film, but this is all Bergman. Despite the heady rumination and weighty existential exploration, there's a universality to all of the director's pondering, an infinitely sympathetic quality rendered in the universal language of cinema.
1. The Silence (1963) A thematic shift from theology to psychology that finds the director at his most abstract and enigmatic. This is probably the most hotly debated Bergman film, but I don't find it nearly as incomprehensible as some do; as the final installment of his "Trilogy of Faith," its impenetrable moods and long stretches of literal silence indicate a spiritual absence. Bergman, through his famous close-ups and depiction of physical gestures, explores the mystery of people, of their faces and forms.