My problem with Citizen Kane is that it's cold. I've watched it several times, and while there are technically many things to admire about it - the structure, the ravishing deep focus photography - it never really stirs me or moves me in the way that so many so-called 'lesser' films do. I never feel any empathy with the characters.
It always comes across to me as a show off piece - an exercise in technical brilliance by a somewhat arrogant young man saying "Look at me. See how clever I am."
And while undoubtedly he was, he had not by that stage mastered the art of involving his audience, and actually making them care deeply about what was happening to his characters.
For me, his masterpiece was Touch Of Evil. As the great Pauline Kael wrote, "He turned a piece of pulp fiction into great art." Even The Lady From Shanghai, while not a great film by any means, is a helluva lot more enjoyable watch than Kane.