For my kit that I am hoping to receive, I picked Sirius Black, Rubeus Hagrid, and Luna Lovegood as the characters to base it on. Here are my reasons for picking these particular characters:
Sirius Black - He was a loyal man, who watched over Harry as best as he could. He could also turn into a dog, an ability which I find really cool.
Rubeus Hagrid - He is a kind guy who is really great with all sorts of odd creatures. I like animals, especially my family's dogs. However, his cooking skills leave a bit to be desired.
Luna Lovegood - I picked Luna because she is an oddball. She is a sweet girl who is as loyal as any Hufflepuff, as brave as any Gryffindor, and as smart and logical as the best Ravenclaws around. Plus, she has funny names for all sorts of odd creatures, like Crumple-Horned Snorkacks.