I wrote about my favourite Jane Austen adaptations here, but I've been meaning to write a post about all the ones that I've seen for a long time - so here it is! (You can also read my thoughts on books based on Jane Austen's novels here.)
Pride and Prejudice (1995 & 2005)
I feel like my opinion is quite controversial here, because I actually really like both versions. Overall, I think the 1995 version slightly wins out, but only slightly. It's longer, and thus includes more of the story, as well as being more historically accurate, but I do also like the more fast-moving story in the 2005 adaptation, and I prefer Keira Knightley to Jennifer Ehle as Elizabeth. The 2005 version was also my first (proper) introduction to Jane Austen, which does bias me in its favour.
Sense and Sensibility (1981, 1995 & 2008)
The 1995 Emma Thompson adaptation of Sense & Sensibility is one of my favourite films, and I basically love everything about it. Even though they did add in some things that weren't in the book (such as giving Margaret a much greater role in the story and developing the start of Edward and Elinor's relationship a bit more), I mostly approved of these things. I think adding to or developing certain parts of the story is different to changing things (although they did change a few details), and the adaptation very much captures the spirit of the story.
The other two adaptations are pretty good too. They both have the advantage of being longer, so were able to include some things that were left out of the 1995 version (although they are still both under three hours and so still leave out some good bits; there needs to be a longer miniseries adaptation of this). The 2008 BBC version is very good, although there were some things that bothered me (such as the dramatic music which plays whenever Willoughby and Colonel Brandon look at each other, even before they have any particular reason to dislike each other), and it lacks some sort of charm that the 1995 version has, although I couldn't tell you precisely what it is. The older BBC adaptation is less good in terms of casting and acting and so on, but it's still quite enjoyable, and does stick more closely to the book. (Basically, I love the story, so am likely to enjoy any reasonable adaptation of it.)
Mansfield Park (1983)
Emma (1972 and 1996 (ITV))
This is an easy choice; I liked some things about the 1972 version (it has possibly my favourite portrayal of Mr. Knightley), but overall it wasn't great.
The Kate Beckinsale version, on the other hand, I really really like. It is quite short, so the story moves quickly which means it can be a little bit confusing (and hard to keep track of who is supposed to be in love with who at which point in the story), and necessarily quite a lot of things are cut; and also, the ending is a little bit random and doesn't really make sense. But I do think it is a really good film.
I haven't seen the more recent BBC adaptation yet, which is something I do need to rectify. (I actually watched the first half of it ages ago and didn't really get into it, but that was before I was properly introduced to Jane Austen. I also think Emma is a story which improves upon acquaintance; I definitely appreciated it more after seeing it once or twice.)
Northanger Abbey (1987 and 2007)
The 1987 version is really terrible and downright creepy. (I watched it before reading the book, so didn't expect to enjoy it that much and was quite surprised when I did.) The 2007 version I think is quite good, although I've only seen it once and don't remember it that well; it was good, but not remarkable.
Persuasion (1995 and 2007)
Neither of these adaptations made a deep impression on me; I don't remember very much about either. I do remember enjoying the 1995 version. The 2007 version is also pretty good up until the last ten minutes or so which are just odd and make no sense. The endings of the book and of the 1995 film are much better. So I would probably recommend the first version.
I also quite enjoyed Death Comes to Pemberley, Lost in Austen (mostly) and Becoming Jane (although it's been a few years since I last watched it).
Also, webseries! I quite enjoyed The Lizzie Bennet Diaries, although I didn't think it was amazing, but I really enjoyed From Mansfield With Love. I've started watching several other webseries adaptations but haven't got that far - I'm not very good at watching these consistently when they come out. Let me know if you have any suggestions as to what else I should watch!