Galaxy Express (and pretty much all of Leiji Matsumoto's work) has very slow pacing, which, in my opinion, makes it less awesome than it might otherwise be.

I will recommend that you read Pluto by Naoki Urasawa. It's a retelling of a story arc in Osamu Tezuka's Astro Boy called The Greatest Robot On Earth, except where the original was written for children, the retelling was written for adults, (and specifically for the adults who had read the original as children.) On the surface it's about extremely powerful robots fighting and destroying each other. It's also about questions like "are robots people? Do they love? Do they hate? Do they mourn?"