The obvious answer is an animal like form you associate with yourself which represents who you are on the inside...but put yourself in my shoes. I have dozens of sub personalities, and three additional fully realized personalities swimming around in my head. Its hard to throw down a "true" fursona in my case, but I want to type it out anyways to get this puzzle out and about.

I used to think I was more dragon than anything else, I love dragons and have been mesmerized by them quite a bit.

Then I realized I was stranger even than the grandest of Wyrms, so my fursona evolved even further into that of the Senkai hence Sakura, my deepest most trusted personality, my original imaginary friend became my identity.

But my life is full of experiences and each new chapter provides a new possibility, new characters, new friends, and new discoveries, Sakura is evolving as a character, into what I'm unsure of but I do believe it will be amazing.

Please, Tell me how you see my beloved Sakura, I want to learn more about her, she is far more than a simple character, she is my closest friend, I dare even say my sister.