23skidoo, you are not alone in the idea of Doctor Ten/Donna Noble. I've really not done any real shipping of DW yet (still a new fan), but after thinking about the companions Ten had in his three years, the one I think would actually be the best fit for him is the one who had absolutely no interest in him except as a friend. But Donna would be PERFECT for him. She really helped temper him and pull his attentions to the individuals instead of always just looking at the Big Picture.
So, yeah, that'd be my pick for this thread, too.