So writing about the Golden Age Post below made me think, what's your favorite obscure Spiderman story/issue. I'm not talking about something everyone seems to love like the Sin Eater saga or the Mark Millar 12 part arc, I mean an issue that you love that you never see in the usual list of classic Spidey Stories.
The one that made me think of this was mentioning the Firelord story, which I really think is a great story that is never mentioned. I guess because its kind of similar to the Juggernaut story a few years earlier as they both are about Spidey being completely outmatched but fighting on anyway. However since I hadn't read the Juggernaut story until last year (in that Wizard top 10 trade), to me that Firelord story was one of the more memorable ones of my childhood.
However I think my favorite story that never gets mentioned is Spidey vs Venom on the island (around issue 345 I think). I think this is the best of the Spidey-Venom stories and it really felt like the climax to all the other Venom stories that preceded it - - as after months of stalking him (inbetween prison stays), Venom finally gets Spidey in a place where he can't run away or get help from the FF anymore. Plus Venom debuts all sorts of cool new tricks in this story. (the water camouflauge scene is a real favorite of mine as it feels like something out of a movie). Again the age you read these is everything but this to me at that time was one of the most intense Spidey stories I ever read. And even Spidey realizes he can't outfight Venom so he outsmarts him and ends the immediate threat to his family once and for all. (Plus the covers for those two issues are pretty tremendous - - as JR notes Venom is probably the most visually interesting of all of Spidey's villains).
There's also an early issue of Spiderman Unlimited with him and the Torch that I love. I always like a good Spidey-Torch teamup, and the whole "Webs Away" thing (Spidey looking for battle cry of his own in answer to Torch's "Flame On") amused the heck out of me in that one.
If I was to pick a recent story, I would say I absolutely loved the Spidey-Felicia story in Many Loves Of Spiderman this year as it was very funny, light-hearted (in a way modern marvel is sorely lacking) and charming.