While not my favorite princess of all time, I think the one with the most attractive character design is the sleeping beauty herself, Aurora. I don’t think I’ve ever seen a “bad” artist rendering or merchandise sculpt of her. I especially love the way she looks in this image: hail to the Princess Aurora, indeed.
I gotta say, even though the tale of Sleeping Beauty as a whole isn’t a personal favorite- I think its visual elements and Tchaikovsky-infused score make it a particularly well-made animated film. And certainly one of the most memorable. Who among the Princess roster wins your vote in a beauty pageant?