Gosh, I'm super late to this.
Hah, well I'm far more late than you are. In part because I hadn't yet discovered the Gang of Five when this showcase was introduced. But I wanted to chime in with my thoughts on my favourite flathead regardless.
What about Littlefoot makes him your favorite character?
Littlefoot is a terrific protagonist. He is certainly my favorite character. That was decided for me as soon as I saw the original movie. It's a bit hard to articulate why exactly, but he's the first character I connected with in the series. I guess because he's at the heart and center of the original, but even in the sequels I'd still probably say he's my favorite. Just a kind-hearted, wholesome, and loveable little dino all around.
Personally, I think his most awesome moment is in the first film. After his nasty row with Cera and the gang splits up, and the other kids ditch him and all go with Cera. Next to his mother dying, that was the part where I felt the most sad for him. But then what does he do? He goes back for his friends anyway, and manages to save them all from dying horribly. That's a true hero right there.