Ryan
I ship Ryan and Cassie. I want the Doctor/Sam to either get together with the blonde chic or to get together with a character who has yet to be introduced on the show. I would rather Cassie got together with someone who doesn't need her to fix them, someone who is generally whole and is kind hearted and sweet.
I like their chemistry better as well. Like the scene where he was getting them a treat with two forks, and turned to tell her, "No, I am a great friend" and tonight when he was teasing her about, "Your doing that thing where you say it without saying it." He reads Cassie so well and he teases with her, and I think that is a better match-- in the long term. And they have a charm together.
"There is still hope." - Arwen