Finn and Poe

I will admit Finn is my favorite of the new humans in Star Wars: The Force Awakens. He had actual growth and development in the film. His subplot was the closest the movie came to having an actual coherent story. The actor did a fine job allowing Finn to be human and flawed without being pathetic - and also able to overcome those flaws. Had it focused more on his background as a trooper, the sort of life he'd had to lead, it could have setup contrast with the First Order leaders and Kylo Ren, one who intentionally indulges his flaws.

This is why Poe is such a great foil for Finn, since Poe represents the freedom Finn seeks, as well as the greater morality/satisfaction he didn't find with the First Order. As I've said before: if it'd been Poe and Finn only with no Rey (or Rey with a reduced presence, her back story saved for the sequel), TFA would have been greatly improved.