First of all, I LOVE Disney animated films. They're still like my absolute favorite form of entertainment, even though I'm now in my mid-20's. (Them and Studio Ghibli movies.)
As a kid, my favorite character was Simba from "The Lion King." (that was my absolute favorite movie as a kid, so it goes without saying.)
In regards to the Disney princesses, honestly, (and I might be in the minority of MtF's here,) I never really liked most of them too much. I LOVED the movies, but not so much the actual characters themselves. To me, they were too girly. They represented everything that I didn't like about femininity (passivity, a constant focus on love and kissing and other "icky stuff," and things like clothing that I didn't really care about at the time.) [Can't help it... you know, I've always been a feminist at heart.] With that said, though, I really did like a lot of the female characters in Disney films... just not a majority of the traditional princess lineup that little girls tended to emulate, like Cinderella and Snow White. For example, I REALLY liked Nala from "The Lion King." She was almost exactly like my real-life female best friend at the time. And I really liked Ariel from "The Little Mermaid" too, and absolutely LOVED Mulan once I finally saw that movie around age 13. I always loved, (and identified with) girls who could fend for themselves, and had a personality, and opinions, and were more active rather than passive and daydream-y. The only exception to this rule was Aurora from "Sleeping Beauty," because I have always absolutely adored her voice. But yeah, that's my history with it. I definitely wasn't one of those gender-dysphoric kids who wished that he could dress in pretty dresses like the girls, and wear makeup, and all of that other stuff that's usually an early sign that they might be transsexual.
Honestly, if you want a female character from an animated film that I actually did really emulate and identify with, I'd go for Nausicaa from the Studio Ghibli film "Nausicaa of the Valley of the Wind." (My avatar, actually.) American animation actually has a nasty tendency to always cast girls in the "damsel in distress" role, or the role of the "sensitive one," or just the "pretty object" role. And that is REALLY far away from my female personality (God, I DESPISE these uber-feminine gender roles, just as much as I despise uber-masculine gender roles.) So there was a real glaring lack of female characters that I could actually identify with growing up. It was when I started watching Studio Ghibli films in high school that, for the first time ever, I really started saying "OMG, that's me" when I finally got to watch characters like Nausicaa, Sheeta, Chihiro, and Shuzuku Tsukishima, the likes of which sadly usually don't exist in American animation.