Which of these Comic Books/Graphics Novels should be heralded as the best of the medium?

I voted Dark Knight Returns.

Chris Claremont's X-Men has so much creativity and good character work but it's rough in places, especially the beginning, so I'm not sure if it would be considered the best comic book run.

I also never finished Claremont's run, but I read most of it, and The Dark Knight Returns is consistently better.

Although, I don't think consistently good doesn't make something better since I think Batman Year One is consistently better than The Dark Knight Returns, but Dark Knight Returns stands out more creativity-wise so it gets a bit of a boost.

Stan Lee's and Steve Ditko's Spider-man is more consistent than Claremont's X-Men, and while it's not as creative or epic, I think it's better.

Too many good choices

Probably Maus or From Hell.

Hellblazer, with its 300 issue run, the series managed to tell a coherent story with deep & complex themes and touching upon a lot of genre tropes rarely seen in superhero comics.

Maus