Fanny and Alexander
I wouldn't go as far as to say it's Bergman's best film, I think that's Persona still, but it's still amazing. People probably like it the most because it's more "accessable" than his other popular movies.
Everyone knows the story, this was going to be Bergman's last project so he put his whole Bergussy into it blah blah blah. But it really does feel that way, the set design, costume design, cinematography, etc are all probably some of the best of his career.
I'll be honest, after watching the 5 hour long TV version, I'm interested to see what was cut down for the theatrical release.