I mostly love Jane Austen, Pride and Prejudice and Persuasion are the favourites. I'm currently re-reading Sense and Sensibility - still very good and I like it better than Emma, (who, quite honestly, the more I've read it the more I dislike). Northanger Abbey and Mansfield Park I have only ever read once each.
Actually what I say about disliking Emma isn't exactly right. It is a well-told tale, well worth reading, but it is difficult to truly love a book when you don't actually like the heroine. It certainly wouldn't be the first Jane Austen book I would recommend anyone read. Mansfield Park and Northanger Abbey also both have heroines I don't get on too well with. Persuasion, as the last book she wrote, has the most mature and well-rounded main character, but it is for a very good reason that P&P is so well loved, the main characters are so interesting and lively.
I got into them when I was about 15 or 16 when the Colin Firth version of P&P was on the TV. I find that I don't enjoy the adaptations of Jane Austen too much now - I generally hate watching adaptations of any favourite book, I always see the bits of the book I enjoyed that they decided to cut or, with Jane Austen, you lose a lot of the satirical edge. The recent film adaptation of P&P was OK, and I found that the film adaptation of Mansfield Park was a big improvement - they made big changes to the way the main character is; Fanny Price in the book is insipid and passive - I may re-read the book sometime soon, see if I still feel the same way.
But I do really enjoy watching TV or film adaptations before I've read a book (watching Bleak House got me back into reading Dickens, having read a couple in my teens) or sometimes I find I like adaptations of books that I found a bit difficult (Middlemarch for instance as well as Mansfield Park) since I don't mind if they chop it or change it so much.
If you want more background on Jane Austen and her books, "Mastering the Novels of Jane Austen" is an excellent book to read, though quite technical.