Ginga Tetsudou 999, Casshern Sins Recommendations
I'm really surprised noone has mentioned these two before. They are really similar. They're both dealing with philosophical themes concerning death and what it means to be alive, and dealing with consequences of your choices in life. They're both pretty dark and slow-paced animes about a few characters travelling around and discovering their own truth from talking to people they meet along the way. They both also deal with conflicts between robots and humans.