1. Both were going to die from sicknesses
So which is better?
Kaori is by far the better of the two. Because she is in an anime series, instead of just a movie she gets a more advanced and elongated progression of plot and character. This gives her character the capacity to really grow a lot more than Sakura could have through the entirety of the movie. Furthermore, Kaori wasn't as desperate for the touch of a man as Sakura was and that whole plot-line turned me off. I thought it was a desperate attempt from the writers to really try and build her character upon some form of foundation but the foundation itself was relatively weak.
I guess what I'm trying to express is that movies tend to be too short to really explore the real nuances of characters that a longer anime series can and therefore Kaori > Sakura.