Every time I read Antony and Cleopatra I'm more impressed. Towards the end of his very long life, my old English teacher - I never knew a man more deeply immersed in Shakespeare - came to rate it as second only to Lear. Tennyson died with Cymbeline in his hand, his finger marking the last words he read, from the reconciliation scene between Posthumus and Imogen.
Perhaps it is somewhat trite to claim HAMLET as a favorite, but for me it is the ultimate Shakespearean play. This may be influenced by the fact that I have taught the play to so many classes over the years. I am never disappointed when rereading it and teaching it because I always discover something new. As Harold Bloom has said, it is the "poem unlimited."