Do this but with rebooted Valiant instead. Internally consistent writing and worldbuilding, excellent art and writing teams, unique and fun takes on heroes... it's ideal:
https://www.reddit.com/r/valiant/wiki/readingorder
Oh nice! I might do this... I bet most of it is on Comixology Unlimited too.
OP: If you're really intent on doing this, start by reading a series up to some predetermined point. Maybe just read Amazing Spider-Man 1-110 (which is where Stan stops writing). Something like that.
Then go to Uncanny X-Men. 1-66 are pretty uneven, Stan & Jack do the first 20 issues, then Roy Thomas takes over up to 44, and then it becomes writer hot potato until 66, the final issue. It's all a bit of a mess, but the middle part is okay, and Neal Adams draws a few issues at the end. But then when it comes back after a seven year hiatus, it's absolutely phenomenal!
Fantastic Four holds up pretty well too, though. I think so at least. It's very episodic and Star Trek TOS/Twilight Zone like during those first 100 issues or so.
Iron Man's book, Tales of Suspense is pretty good too. I really like Don Heck's art and how different it is from Kirby and Ditko. Ditko is messy, warm and expressive, Kirby's is so strong and powerful, but Heck's is perfect for Iron Man. So clean and precise. And I think he hits that dapper early 60's look so well. And a few years later he takes over Avengers and starts using an inker, but those early Iron Man books (Tales of Suspense, that is) are him inking too and they're really good.
I dunno, I think it's going to be really tough, but good luck!