I think HMS Surprise has to be my favorite, because it's got espionage! Hurt/comfort! Debauched sloths! It's got a lot of good Maturin scenes, and I must admit that as much as I adore Aubrey, Stephen is one of my all-time favorite fictional characters. (I have a soft spot for characters that are very, very good at what they do but are absolute messes in any other situation.)

And yes, Post Captain is delightful. :D Pride and Prejudice and Post Captains!