Well, since you made an account just for this, what else can I do but oblige you (after making you wait weeks for it)?
The Flash, perhaps more than any other character in DC’s stable, represents the strength of the legacy hero: the passing of the mantle from mentor to protege, with each successive version having their own strengths and weaknesses. So here’s a look at the different versions of the Flash.
(Full disclosure: all the Amazon links here are actually Amazon Smile links. Amazon rejected my application for an Amazon Associates account a while back because they hate Tumblr, so if I can’t benefit monetarily from making these posts, at least a few cents can go to a non-profit of my choosing. In this case, it is a local (to me) not-for-profit volunteer community band/arts educators. It doesn’t cost you any more, and 0.5% of money spent via those links goes to help. You can choose not to use these links if that’s a thing you’d rather do, but there you go.)
GOLDEN AGE FLASH
The original Flash was a guy named Jay Garrick. He breathed in some hard water fumes and then ran around with a bucket on his head. He is pretty cool.
The bad news is, as far as I can tell, there is no in-print collection of Golden Age Flash strips. The good news is, since—as I said—the Flash is all about legacy, he tends to show up plenty later on.
SILVER AGE FLASH
The popularity of superhero comics fizzled somewhat following World War II, and the Golden Age of the comics was over by the early 50s. However, by the mid-50s, a couple of enterprising editors decided to revamp the superhero concept by adding in various sci-fi elements for the atomic age.
The book widely considered to have kicked off this new age—the Silver Age of Comics—was Showcase #4, the first appearance of the second Flash, Barry Allen.
The Flash stories of the 50s and 60s were primarily created by John Broome and Carmine Infantino, and while the early stories from their run can often be highly formulaic—even in comparison to contemporary comics—they introduce many of the key elements of the Flash mythos: the Rogues, Gorilla Grodd, Iris West, Wally West aka Kid Flash, the stretchy detective Elongated Man, and so on.
Furthermore, it is within the pages of the Flash that DC introduces the concept of its multiverse; the idea of Earth-2 being a plane of existence where all the Golden Age heroes lived and fought begins with Barry meeting up with Jay thanks to some savvy vibrating.
Plus, you eventually get awesome shit like this:
If the silly inventiveness of the Silver Age is not to your taste, well, that’s your own cross to bear, I guess, but if you want to see the real roots of the modern Flash, there are a couple of ways to get these stories:
The Flash Omnibus collects the earliest adventures of the Flash from Showcase into his own title. This volume collects SHOWCASE #4, 8, 13 and 14 and THE FLASH #105-132 (the series resumed the numbering of the original Golden Age series) in color, in a big, fat harcover. Now, even with Amazon’s pretty deece discount here, you may not want to drop sixty-plus bones on the Flash. In that case, you can get:
Showcase Presents: The Flash This series of volumes contains the same material as the omnibus, but in black and white, on lower quality paper, but for way less money. While the omnibus (so far) only collects the first 30ish issues of Barry Allen’s adventures, there are four Showcase volumes of Silver Age Flash available (not technically in print as far as I can tell, but they’re all still available for decent prices on Amazon), which will altogether get you about 80-90 issues. These books are, in my estimation, the best value. But! If you really want to see this stuff in color, but don’t want to buy the Omnibus…
The Flash Chronicles collects, once again, the same material, but in smaller chunks than the Showcases, but in color.
You have options, is what I’m saying.
ONE LAST HURRAH (for now) WITH BARRY ALLEN
Showcase Presents: The Trial of the Flash by Cary Bates and Carmine Infantino is the last (at the time) story of Barry Allen. While most Showcase volumes reprint Silver Age stories, this one collects a tale from the very end of the Bronze Age. This massive tale (unusually long, especially for the time) represents the final two years of the Flash before Crisis on Infinite Earths. This is the tale of Barry going on trial for the manslaughter of one of his greatest foes, the Reverse Flash. The story-telling will probably read as super old-fashioned to a modern reader, but if you’re interested in one of the major sagas in the life of the Flash, well, here you go.
OKAY SO WHAT HAPPENS NEXT IS
Barry dies in Crisis on Infinite Earths. You will notice I did not link to that book. Don’t worry about it. There is literally no reaction that a new reader would have to Crisis other than “What the fuck am I reading and why the fuck am I reading it.”
Here’s what you need to know: Barry dies saving literally everyone. He’s a big damn hero.
So that leads us to
Taking up the mantle after Barry’s death is Wally West, the nephew of Barry’s girlfriend and later wife Iris West. Way back in the 50s stories, he miraculously got Flash powers in the exact same way as Barry, so Barry reluctantly makes him his sidekick, Kid Flash, who goes on to be a founding member of the Teen Titans.
The best writer of the Wally West Flash is Mark Waid, who wrote the book for a long time, with various artists, including Salvador Larocca and most notably Mike Wieringo. Unfortunately, his run has been only sparsely collected.
Let me be clear: if you buy only from one section of this list, make this that section. Waid’s Flash is the best Flash, period.
Here’s what’s available, roughly in order:
Born to Run by Waid, Greg Larocque, et al. Great intro to Wally and his history as Kid Flash.
The Return of Barry Allen by Waid, Larocque, et al. I believe this was just certified on War Rocket Ajax as the best Flash story ever, so there you go.
Impulse: Reckless Youth by Waid, Humberto Ramos, et al. Impulse is Bart Allen, grandson of Barry Allen from the distant future, come back to annoy Wally. This collection includes—I think—his introduction in the Flash, plus the first few issues of his solo series, which would include what Chris Sims has boldly claimed is the greatest single issue of all time. This is, as far as I know, the only available collection of the Impulse solo series.
Terminal Velocity by Waid, Wieringo, et al. This is the story that introduces the idea of the Speed Force, the source of the Flashes’ powers. It has one millions speedsters in it and is pretty awesome.
Dead Heat by Waid, Ramos, et al.
Race Against Time by Brian Augustyn, Waid, et al.
As far as I am aware, these are the only collections of Waid’s Flash run, and they’re all technically out of print, but Amazon has them all for decent prices if you don’t mind owning a used copy.
Here are some other cool Wally stories:
Emergency Stop by Grant Morrison, Mark Millar, and Paul Ryan. This is the first half of superstars Morrison and Millar’s work on the Flash. Plenty of cool stuff here.
The Human Race by Grant Morrison, Mark Millar, and Paul Ryan. This collection is pretty awesome. It features a story of the Flash racing Sonic the Hedgehog (basically) across the universe and then introduces the Black Flash aka the Grim Reaper for fast people.
The next major writer on the Flash is Geoff Johns. This run is notable for its work fleshing out the characters of the Rogues. His run, with art primarily by Scott Kolins, is collected in three omnibus volumes.
You might also want to get Final Crisis: Rogues’ Revenge by Johns and Kollins. It is pretty good.
OKAY BUT THEN WHAT HAPPENED
Since you said that you’ve read the New 52 Flash, you might know that Wally isn’t the Flash anymore. Barry is.
Due to the events of Infinite Crisis (not linked for reasons), Wally and his family go to an alternate reality. Bart becomes the new Flash. Then Bart gets killed. These stories are terrible.
Barry returns in Final Crisis (which is not very Flash-centric, but is awesome and I’ve already put it on like three of these For the Uninitiated lists, so you should have it by now). Then even though there is still a perfectly good and way more interesting Flash still available in Wally (who has come back from that other dimension, obvs), someone decided that Barry should be the Flash again.
If you are the kind of person who likes their comics “important” rather than good, here are some books you can buy:
Flash: Rebirth by Johns and Ethan Van Sciver.
Dastardly Death of the Rogues by Johns and Francis Manapul.
The Road to Flashpoint by Johns and Manapul.
Flashpoint by Johns and Andy Kubert.
And this literally leads us to the New 52, which happened (in-canon) as a result of Flashpoint. The good news is, the New 52 Flash stories are actually pretty good, and the art is beautiful. Those stories are collected in these volumes:
Move Forward by Manapul and Brian Buccellato.
Rogues Revolution by Manapul and Buccellato.
Gorilla Warfare by Manapul and Buccellato.
Reverse by Manapul and Buccellato.
and I guess there’s a forthcoming volume 5.
My suggestion for after that?