I miss Mattie. Like the rest of you, it wasn't until after her spoilt brat phase that I started to like her.
I've really enjoyed most of her storylines, from her rebelious stage after Ric and Cassie got together to her bulimia and her relationship with Lucas. I always lover her and Luc together but when that fizzled out I began to love her with Ric. I agree with bttb-rox!, you could see the difference in maturity in the two relationships and I think it really showed Mattie growing up.
One of my favourite episodes with her is when I think (bad memory warning!) her, Ric, Cassie and Luc are playing truth or dare and she has to stand on a chair in the diner and sing I loved watching that.