Well, only Natalie and Dan because I love Dan and because they would probably be the most neutral couple. and because Natalie reminds me of me, fashion sense, and Dan is like someone from my school. And because Amy reminds me of that someone's annoying, over-protective older brother, not mentioning any names... but otherwise, I don't ship any of them, as I think both couples don't match for each other.
I really can’t see Dan in a relationship with anyone. Besides, he despised Natalie and was just sad about er death because he’s a good person. He was more sad about a man he barely knew’s death than Natalies, so I can’t see them together. Ian never really liked Amy, though Amy liked Ian, and he referred to her as “little cousin” so I can’t see them either. It’s also hard to see Ian getting over himself to be in a relationship honestly, he’s just too snobby (I love him). So my answer is neither but I guess I’ll pick Amy and Ian since at least it was canon Amy liked Ian, which is a lot more canon that Natalie and Dan.