Yes, I would love to see a film that told a more realistic story of Sisi. Romy Schneider is a lovely actress, but those films don't have that much to do with the truth. I've heard that Romy hated the inaccuracies of the films. And I'm under the impression that most Austrians who know anything about their own history know that those films are just romantic fairytales and that the reality was something quite different. But those films tend to annoy me because all too often, they're all that foreigners know about Sisi, and that means they really don't have a truthful image of her.
Other than the Sissi films (which I saw 15 years and a few biographies too late... I'd probably have liked them as a child) I've only seen the Kronprinz Rudolf TV film, with Sandra Ceccarelli as Elisabeth. I thought she did a pretty good job in the dreamy melancholy of the Empress, even if the character was maybe scripted a bit too nice - but that's not the fault of the actress.
But I was very glad to see Imperial_Grounds mention the Elisabeth musical, which is quite a popular musical in Europe, though no English version has been made so it isn't so well known in English-speaking countries. I love that musical - it's actually what got me into Elisabeth and other Habsburgs and Wittelsbachs, of course I'd heard something about them before but I hadn't realised how interesting they were. And I find that out of the fictionalisations of Elisabeth etc. that I know, it's the most accurate a representation of her life and character. Even though as it's a musical and you can't fit in everything, very many things have been left out, and it's actually got a very fantastical approach. Elisabeth's story is narrated by Lucheni, her murderer, and her life is represented as a battle for independence on the one hand and as a romance with Death on the other. Death is a character in the musical, an attractive young man who loves Elisabeth and tries to get her - this accounts for many of the tragedies of her life as well as her depression and longing for death.
There have been lots of excellent actresses playing Elisabeth in that musical, who I've felt have really portrayed her character very well, both positive and negative sides - she isn't just a heroine there, she is also a deeply flawed human being whose strength turns against her and who commits her own big errors. Pia Douwes, already mentioned here, is a really great Elisabeth; another famous one whom I also love is Maya Hakvoort, who plays Elisabeth on the DVD made of the Vienna production of the musical. There are also many other good ones. Annemieke Van Dam of the current German tour of Elisabeth looks incredibly much like the real Sisi and seems to play her with lots of spirit and emotion. My own personal favourite is the Hungarian Nikolett Füredi, whom I saw last January in Budapest. She had a unique emotional depth and strength and brought across Elisabeth's dark side very well, her fragile emotional balance, her aloofness and her longing for Death. I could post some pictures of this musical if you want, though I don't know if there should perhaps be a different thread for the musical, as this thread is for films and cartoons, not the stage.
There is also a Rudolf musical, but it doesn't have Elisabeth as a character. The Elisabeth musical has Rudolf, though.