Around that time, though I think I've read the revised editions of those and never got around to reading the actual first one (Soviets)

It is interesting to have some historical perspective, regarding comic books, and to know where the medium has been or come from, but life's too short for reading comics you don't enjoy. I used to feel almost obliged to wade through certain old comics -- even if I didn't like them -- in some silly attempt to become acquainted with the "important classics". These days, if a vintage series doesn't do it for me, I ditch it pretty quick.

In answer to the main question, the 1950s sci-fi, horror or detective stories (Weird Science, Rip Kirby, Tales from the Crypt, Dan Dare etc) are about the earliest I can go back and still enjoy what I'm reading. I really can't handle Golden Age comics at all; they're just too crudely drawn and written for my tastes. I do like the Dick Tracy newspaper strips from the 30s and 40s though, but that's an exception. I also enjoy the Tintin books from the 30s and 40s, but they're a slightly different thing. The American Golden Age comics that I've read have always bored me rigid as a rule.

I love Silver and Bronze Age comics though...particularly Marvel's Silver Age stuff. It is hideously dated in some instances, and you have to make allowances for that, but in no way does that detract from my enjoyment of those comic books.

To be honest, not all Silver Age Marvel books are created equal: the early X-Men comics are pretty terrible IMHO (interesting concept and all, but lousy comics), while Amazing Spider-Man is the very best of '60s Marvel, if you ask me. The early issues of The Avengers are quite basic and my enjoyment of the series definitely picks up once the series gets going, say around issue #30 -#40 or thereabouts. Personaly, I've always found Thor as dull as dishwater, but the general consensus is that the '60s Thor stuff is actually really good. Try the Silver Age Nick Fury stuff (especially the Jim Steranko stuff) and the Steve Ditko era Dr. Strange too...they're both excellent comic books.

Who knows though, maybe old '60s comics just aren't for you.

I'm comfortable going all the way back to the Golden Age.

As a comics historian, I've read comic books from every decade since Max Gaines invented the modern floppy in the early 1930s. I can read any of them and enjoy them but my preference is for material published between 1955 and 1986. And I have to say I'm at the opposite end of the spectrum from my friend Icctrombone: I want a comic it takes me half an hour to read. Modern comics, as a rule, are way too quick a read to satisfy me.

Cei-U!
Wants some meat in that sammich!

* Not true, as it turns out. It was Gaines, however, who first proposed selling comic books on newsstands instead of continuing to market them as prmotional giveaways.

The 60's are mostly the furthest back I've go. Silver Surfer (though I read them in the Fantasy Masterpiece reprints and then the actual last four issues) was the oldest at the time in the 90's (only a few years into reading comics) that I had read. Being familiar with the character from the then ongoing series, I enjoyed the difference in them, but I haven't gone back and read them often. Since then nothing I've ventured out to read has taken me further back than the 60's. I don't know if that is intentional, or it's just that nothing older than that interests me.

Now with all the available material in TPB, I have bought and/or read from the library a lot of Essentials and Showcase volumes of titles I previously had never read, or only a few issues of. I came away really liking House of Mystery, though the later stuff than the earlier. I enjoyed all the House of Secrets volumes, but never was able to finish the first Challengers of the Unknown book. It did, for me. become a chore, and I found myself really just saying, hey this is Kirby stuff you need to get acquainted with the man, but never really enjoying it, so I quit and haven't opened it up again. Early Avengers, FF, Thor and Spidey are that way for me too. All these titles hit the ground running for me sometimes in the 60's and really in the 70's.

One other example I can think of is a book of horror comics along with some history about them. It's in a book (novel) format and gives examples of horror comics throughout history. Sorry I cannot remember the title. And I read the whole book, the history and the reprinted comic stories themselves (not always the whole comic, just usually one story within an anthology comic) and found the early 40's (maybe went back to the 30's) and 50's stuff just unreadable. As someone mentioned I think being a collector to start has spoiled me to spectacular art, and it's hard to appreciate something that isn't what things are now. Kind of like my kids with NES as oppose to the Xbox 360 or PS3.

So as Confessor says, I finally decided that if I don't enjoy it, why bother with it, no matter what cultural influence it is suppose to have. Just read what you like. I do however like reading ABOUT older comics, like in book about the history of. It's the actual material that I have yet to find interest in something that old.

I can go back to the 60s with Marvel.  I think Spider-Man and Fantastic Four are the best of the early period.  Avengers is really not very good (apart from the first issue), but I did get through the first omnibus. 

For DC, bronze age is the earliest I like.

I've tried reading some golden age books and I can't get into them at all.