The Lee/Ditko run, the Lee/Romita Sr. run. They're the definitive ones.
Pretty much everyone just repeats the themes from them.
Then I'm partial to the Peter David run, you know, the one with When Cometh The Commuter, the first appearance of Ashcan, and The Death Of Jean DeWolf that set up the creation of Venom years later.
And the David Michelinie's run, with MJ and Peter as a young married couple struggling to make their careers work while juggling crimefighting.
I never understood why Michelinie gets so much shit around here. His run on Iron Man was the best, most consistent, he has Tony acting like an actual A-list rich guy, and never resorts to stupid gimmicks like turning Tony into a kid, or replacing him with Doom. His run on Spider-Man was just as good, this was the last great run before fucking clones, and fucking Carnage, and fucking Carnage clones, and android parents, and Aunt May dead and alive, and fucking Tony Stark ruining everything and fucking One More Day ruining everything forever, and why the fuck is Ultimate Spider-Man even a thing when Peter is alive? And before Spider-Girl and Spider-Gwen and Spider Island and Spider-Verse and Spider-get-me-the-fuck-out-of-here.
Also I'd recommend the Japanese Spider-Man manga from the 70's, it's fucking dark.
Bernie Wrightson's Hooky graphic novel was amazing, but no-one ever talks about it.