Recently reread "Nothing Can Stop The Juggernaut".
That should really be up there. Along with the rest of Stern's run! SO GOOD!
Just to explain: both Peter and Mary Jane have a character development arc across the issue, and Mary Jane is awesome and gets to save Peter twice (I'd argue that it's not so much subtext as text that that is why she agrees to marry him). The two villains span the range of Spider-man's world: Alisdaire Smythe is a science fiction villain, just a good a villain as he was on his first appearance, having extremely limited tunnel vision and focus but being frighteningly intelligent inside that limited focus, while Philip Watson is equally good as a villain in a far more grounded way.
Petrus Maria Johannaque sunt nubendi
Damn this is tough I guess for me right now its issue 300 venom first appearance Peter and him first fight and the issue ends with the return of the Red and Blue suit
"He's pure power and doesn't even know it. He's the best of us."-Matt Murdock
"I need a reason to take the mask off."-Peter Parker
"My heart half-breaks at how easy it is to lie to him. It breaks all the way when he believes me without question." Felicia Hardy
-Kraven's Last Hunt
-The Child Within
-The Lost Years
The Night Gwen Stacy died is definitely a frontrunner for me, but I probably need a bit more thinking time.
As an aside, reading through these scans has left me absolutely staggered at the quality and subtlety of the writing. No writer in the last 30 years comes close, aside from maybe Paul Jenkins or Chip Zdarsky at their best.
I knew it was a classic story, but I haven't read it in a while and kind of forgot just how good it is.
I haven't seen as much praise for this story since Wizard is no longer really a thing, but it absolutely is a great Spider-Man story. No offense to any of the creative teams that did Spidey vs. Juggernaut stories after, but I never really liked the follow-ups as much because they ultimately boil down to "Spidey beats this seemingly unbeatable foe yet again" and it loses something. Second verse doesn't hit as hard as the first.
Just to add a different answer, it's not the best, but one of my favourite is The Superior Spider-Man #31. That close-up with Green Goblin saying "It's you" is incredible. A beautiful way to end the series.