Most important person in Lincoln's life

[Eva Elisabeth]

I agree with you on his family (and I'd add his sister!), but I personally think Ann Rutledge's total, long-lasting influence is much overestimated. Many people have a first-love experience which influence them for that more or less brief period in their life, but not forever when they find a new, especially lifelong partner. I think Mary not only had a much longer but also a supportive influence on his career, thus on his life. And she bore his children.
I think his admiration for Henry Clay also shaped him, at least his career and political thinking and ideals for a long time, and thus his way in life.

As for forming someone's character - overall I think a lot is just inherent (likewise is "her intelligence came from her side of his family" - inherited "influence"). I know twins (now in their sixties) who grew up doing everything together and were treated the same by their parents. Still they developed different values in life and very different character traits. Actually one isn't treating the other, who's a very sensitive person, very nicely.