I agree that it would be easy to make a list of "Twenty Silver Age Books that are pretty OK."

But if you are trying to do an actual "best" list - and your memory is as bad as mine - you'd be shocked at how much of the very best American comics are published between 1953-1955.  Which means you keep going "Crap, that can't go on a list that starts with 1956."  

I'm not an expert. What I know is Marvel, and even that only so perfectly.

My #1 is without any contenders Amazing Fantasy #15. I consider one story from it to be the most perfect superhero origin which doubles well as a standalone sci/fi morality tail. And the rest of the stories encompass what is generally so great about the whole of the short-lived Amazing Adult Fantasy. The best Twilight Zone-esque stories that I have found in comics.

Other great Spider-Man comics which should be seen as contenders are Amazing Spider-Man #33 and Amazing Spider-Man annual #1. And at least think about Amazing Spider-Man #3, which debuted his greatest villain.

Oh, and #50, where he quits being Spider-Man. Well, if you're going there, maybe #17 should also be considered. And...

*****

What else was awesome in the Silver Age?

Well, Avengers of course.

Avengers #4 should probably go pretty high.

And of course #16 is what they Avengers are all about.

And then of course #57. Introduces Vision. John Buscema at his peak. Epic battle with Ultron. Famous ending set to a classic poem. (The next issue of course gives us another famous ending, but is less strong an issue over all)

********

Speaking of Ditko earlier, he told some great Dr. Strange stories. The best bit is the extended Eternity saga, best embodies by Strange Tales #138, where the doctor comes face to face with the living embodiment of the universe. And how wrong can you go with Nick Fury battling Hydra?

Dr. Strange has the second best origin in comics, and the origin story in 115 is about as good as good gets. Not sure I can in good conscience nominate the issue, as it includes a Human Torch story. And, well, ...

The next best Dr. Strange story is probably 127, concluding his first confrontation with Dormammu. An epic struggle paired with some real complexity. But, while I don't specifically recall the Human Torch/Thing story, it's paired with, I doubt it's the cream of the Silver Age.

*********

While this may be controversial, Silver Surfer is a fine little series. His origin is issue #1 is truly epic and makes for a great sci/fi tale. Excellent battle with Thor in issue 4. But I think the height of it is the battle with Mephisto in #3.

******

Fantastic Four is a fine little series. The whole stretch from #39-60 is comics at their best and it's hard to pin down. The epic Battle for the Baxter Building. Inhumans. Silver Surfer. Galactus. This Man, this Monster. Black Panther. Doom on a flying surfboard. Frankly, you could do worse than take those issues and call that your top 20.

******

That's a start. I'll narrow that down to 10 since it's only Marvel comics. And there are probably DC comics and maybe even others from the decade.

Amazing Fantasy #15
Amazing Spider-Man #33
Amazing Spider-Man #50
Strange Tales #138
Fantastic Four #51
Fantastic Four #48
Avengers #4
Avengers #16
Avengers #57
Silver Surfer #3

That's my contribution. I'll confess to a fairly limited scope of Silver Age knowledge.

Avengers:
3,4,16,56,57,76 Annual 2.

Fantastic Four
5,16,25,26,39,40,48-51

Just to name a few.

To be continued ...

Forget what I said before. This is my list.

1. Amazing Fantasy #15 (Spider-Man)
2. Amazing Spider-Man #33 (The Final Chapter!)
3. Amazing Spider-Man #50 (Spider-Man No More!)
4. Amazing Spider-Man annual 1 (The Sinister Six!)
5. Amazing Spider-Man #18 (The end of Spider-Man!)
6. Amazing Spider-Man #43 (Rhino on a rampage!)
7. Amazing Spider-Man #32 (Man on a rampage!)
8. Amazing Spider-Man #31 (If this be my destiny...)
9. Amazing Spider-Man #11 (Turning point!)
10. Amazing Spider-Man #1 (Spider-Man/Spider-Man vs. the Chameleon)
11. Amazing Spider-Man #3 (Spider-Man vs. Dr. Octopus!)
12. Amazing Spider-Man #9 (The man called Electro!)
13. Amazing Spider-Man #27 (Bring back my goblin to me!)
14. Amazing Spider-Man #24 (Spiderman goes mad!)
15. Amazing Spider-Man #4 (Nothing can stop the Sandman!)
16. Amazing Spider-Man #39 (How green was my goblin)
17. Spectacular Spider-Man #2 (The Goblin Lives!)
18. Amazing Spider-Man #17 (The return of the Green Goblin)
19. Amazing Spider-Man annual 3 (To become an Avenger!)
20. Amazing Spider-Man #47 (In the hands of the Hunter!)

I'm not sure I've read widely enough of the Silver Age to nominate anything to the best of list. I could name a lot of favorites, but the criteria distinguished between best and favorites. I've read a ton of Silver Age Marvel and a smattering of Silver DC, but only a handful of other publishers.

So if we are defining best (and not favorite) what makes best issues?

I agree the Spidey story in Amazing Fantasy #15 in fantastic, but it is only 11 pages out of the 24 pages in the issue, and the rest was decidedly mediocre at best-does that still make it one of the best issues of the Silver Age-does the quality of less than half the book outshine the lack of quality in the majority of the issue? Does one issue in an anthology issue make it one of the 20 best issues of the Silver Age (again it's not storylines, it's issues in the OP's criteria).

Do we accept giant plot holes as part of the Silver Age charm-Avengers #4 is significant because it's the return of Cap, but the plot is built on a house of cards series of coincidences necessitated to make the plot work lots of things just happen to be this way because the story needs it to be that way to make it work, i.e. poorly thought out plot construction-it's not terribly good storytelling really in terms of craft, but it's significant and a lot of people like it because well because Cap and a great Kirby cover, but is it one of the best issues?

So what criteria are people using to determine best other than these are the ones I like the best and they are my favorites(which is not what the OP seems to be after)?

Are we looking at craft? Significance? Entertainment value (the mot subjective of the criteria I have mentioned so far and the one least likely to find any agreement in a best of list)? Popularity? Sales? Some occult combination of these factors? Why are these selections being put forward the best? Without a criteria of best, any nomination is going to be subjective and useless. Best at what? Why best? If it's best, what is it better than? What's the criteria you are using to make that determination? What are the standards you are measuring against? And how big of a sample are you drawing from. No context for the pick, no meaning to the pick.

It's why I hate attempts to do a best of list; everyone making suggestions has a different criteria and most picks are favorites without any attempt to distinguish between the two, which renders the whole thing moot in many ways.

-M

That's my favorite story from my favorite run of superhero comics.*

But it's paired with "Spidey Tackles the Torch" which is among the worst stories from my favorite run of superhero comics.

Honestly, the best way to do this would be to split it into multiple lists of individual stories from anthologies, single issues and multi-issue storylines - although the latter would be really Marvel heavy.**   

Also break it down into decades instead of "Silver Age" which is a fairly useless term unless you're only discussing Silver Age Comics. 

*  Well, either that or Cole's Plastic Man.  
**  But you could count the marriage and breeding of Reptisaurus, and that would be awesome.