Kraven's Last Hunt is great, the Death of Gwen Stacy will always be a milestone, the origin is timeless, Standing up to the Juggernaut was classic Spidey. However, the way some of the stories are talked about you would think his thousands of comics only gave a handful of readable stories.
What Spider-man stories mean the world to you, but never seem to get any love? More importantly, why?
"The Child Within" - from Spectacular Spider-Man 178-184. It explores the childhood/parental issues in Harry, Peter, and even Vermin. Heavy stuff.