Wow, I was coming on here to say Persuasion, and everybody else has said it too.
It really is the best of them, I think. Anne Eliot is such a lovely herione, and deserves every happiness she gets. Persuasion accepts that people are fallible, and gives the chance of some redemption.
I love Mansfield Park now, but hated it when I was a teenager, and thought Pride and Prejudice was much better. Mansfield Park offers the opportunity of redemption, but the two most vital and attractive characters refuse to take it, because they have already become too corrupted by wordly values.
When young. I thought Bingley (in Sense and Sensibility) was touchingly lovely when he quoted Shakespeare, despite how pathetically weak he turned out to be. I thought the situation between him and Marianne was sentimentally tragic, instead of being a depressingly inevitable consequence of his utter crappiness and her tragic inability to see reality with any clarity. Brandon is obviously a great catch in wordly terms, but as a man he is just a consolation prize for her own weakness. And Elinor doesn't do much better, with a bloke who was foolish enough tro be taken in by Lucy.
Now I am older...
I wish Jane Austen had lived a whole lot longer to write more books.