I really think it comes down to a duel between opus 53 and 57. For some reason I can't include any of the last five, even though they surpass the rest in certain ways, and are probably my favorites. I think Beethoven's craftsmanship in opus 53 and 57 is amazing. When I listen to them, I feel a strong sense of satisfaction, of completeness, as if the idea has been fully realized. I think they embody unity.