Captain America was first published in 1941 in Captain America Comics via Jack Kirby & Joe Simon; after super heroes fell out of favour post-World War II, the series struggled, vanished for a while, tried to make a comeback in the early 50s, then folded for good in 1954 after 78 issues; during that time, Captain America was frequently a featured player in other Marvel titles such as All Select Comics, All Winners Comics, Marvel Mystery Comics and USA Comics. He became one of Marvel's flagship characters, often sharing covers with the other two big Marvel heroes of the time (the Human Torch & Sub-Mariner). In the midst of World War II a red, white & blue hero who took the fight to the Nazis - before the USA had even declared war! - he was pretty evocative. His sidekick Bucky even scored his own super hero team in Young Allies Comics.
Stan Lee & Jack Kirby brought Captain America back in 1964's Avengers#4, rendering Cap an indelible part of the Avengers franchise; Lee & Kirby threw out all of the Captain America stories published from '46-54, preferring to have Cap spend the intervening years in suspended animation; thus, Cap has remained "the living legend of World War II." Having retroactively killed off Bucky, Cap was depicted as a man out of time, haunted by his sidekick's death and uneasy about the world he lived in. Starting with Tales of Suspense#59, Lee & Kirby began delivering half-length Captain America solo stories (the other half of Tales of Suspense was held by Iron Man) until the series became Captain America with issue #100; Captain America has been published by Marvel ever since, despite a serious rumour mill claiming he'd be cancelled in the 1980s.
If you want my recommendation in brief, there are two great eras of Captain America: the Lee-Kirby years (Tales of Suspense#59-Captain America#109) and the era of writer Mark Gruenwald (Captain America#307-443). The first three volumes of Marvel Masterworks: Captain America collect the Lee-Kirby years, but there is no definitive series of Gruenwald volumes, just a few representative trades (Scourge of the Underworld, the Captain, the Bloodstone Hunt, Man and Wolf and Fighting Chance vols. 1-2).
Tales of Suspense#79-81 by Stan Lee & Jack Kirby. Of all the Lee-Kirby tales, this is easily the most frequently referenced. The Red Skull - Cap's most repeated enemy in the 40s - returns in modern times, still worshiping evil in spite of the Nazis' defeat. Having obtained the Cosmic Cube, a veritable Aladdin's Lamp of power, the Skull becomes all-powerful...but that doesn't mean Cap can't stop him. There have been many (too many) Red Skull/Cosmic Cube stories since this one, but the original frames it properly; it doesn't matter how superior the Red Skull or any opponent is, Captain America will find a way to stop them.
Captain America#110-111 & 113 were the only three issues written/drawn by Jim Steranko. The plot isn't too remarkable, with Cap fighting the forces of Hydra, led by the memorable new villain Madame Hydra, but the style Steranko brought to these issues have kept them firmly entrenched in people's minds as what a great Captain America story looks like.
However, after Steranko the series fell into the doldrums, despite some nice art by Gene Colan and a great new sidekick for Cap in the person of the Falcon. Captain America#168 was a fill-in story by Tony Isabella and Sal Buscema and delivered a fine tale with Cap meeting the son of Baron Zemo, the man who slew Bucky; just as Cap is haunted by Bucky's death, the younger Zemo has a vendetta with Cap for ruining his father's life. Helmut Zemo had a modest introduction here, but would go on to become an interesting character, not entirely unlikeable and a skewed perspective on what kind of man Captain America was.
I know I couldn't go without mentioning Steve Englehart & Sal Buscema's Captain America#175, the climax to Englehart's lengthy Secret Empire epic, where Cap brings down the Secret Empire on the White House lawn...only to find the Empire's leader is the President! The President commits suicide rather than face humiliation and Cap is stunned, finding his faith in his own nation faltering. He gives up being Captain America, leading us to...
Captain America#180-183 by Steve Englehart, Sal Buscema & Frank Robbins. In these issues, Steve Rogers adopts a new costumed alias: Nomad, the Man Without a County! However, his cape doesn't last very long.
Roger Stern & John Byrne's run on Captain America lasted only from issues #247-255. Regardless, it turned out to be one of the most memorable turns on the series, similar to Steranko in being well-remembered despite its brevity. Captain America#250 addresses the idea of Captain America running for President. It's an outstanding issue because of how it portrays the public reaction; the people want Cap to be their President. They don't care that he knows nothing about politics; they just want somebody they can trust. This story hits on all the angles about the idea of Cap running for President (the Democrats & Republicans both want him on their ticket!), but finally brings it down to Steve Rogers and his personal conviction that his work as Cap is more important than becoming a figurehead.
Stern & Byrne's best multi-part story was Captain America#253-254; Cap looks up some of his old World War II allies, the British hero Union Jack and his daughter Spitfire, now both quite old and Union Jack nearing death's door. However, Jack is convinced their old vampire foe Baron Blood is still alive; unable to slay his foe alone, he brings in Cap. The showdown between Captain America and Baron Blood was notable for how violent it was for the time, with Cap beheading Blood in the climax; this story also helped keep the Union Jack identity alive as young Joe Chapman assumes the role (which he bears to this day), giving England a pretty cool-looking super hero.
Captain America#255 was Stern & Byrne's farewell; appropriately, they took the series back to its beginnings with a retelling of Captain America's origin. Kirby himself had told the origin on three separate occasions, incorporating different names and details each time. Stern & Byrne put everything together in way which made all three versions accurate, which is a pretty neat feat. It also filled in little details like how Cap went from his triangular shield to the rounded shield and how the Red Skull helped inspire his costumed identity. This remains the best single-issue adaptation of Cap's origin.
To explain the Captain America stories from '46-54, it had been decided by various writers that three different replacement Captains America had taken up the role while Steve Rogers was thought dead. In Captain America Annual#6, J.M. DeMatteis and Ron Wilson told an offbeat story where all four Captains America are united. The 3rd Captain America, Jeff Mace, formerly the hero Patriot, is dying of cancer; all he wants is one last challenge and he wants to face it at the side of his idol, the original Captain America. Thanks to a cosmic being, Mace gets his wish, but it's not everything he'd hoped for. It's a bittersweet story and made me an instant fan of poor Jeff Mace, the replacement Cap who never seemed to have his moment to shine.
For J.M. DeMatteis' farewell to the series in Captain America#292-300, he set up a "final fight" between Cap and the Red Skull. With the Skull nearing his end from old age, he's decided how he wants to die: at Captain America's hands. Of course, he doesn't want Cap to live too much longer after him, either. In the issues building up to this, the Skull does all he can to tear Cap down, hoping to drive him into a murderous rage, while poisoning him so they'll die together. Cap keeps trying to reason with the Skull, but the Skull is fundamentally incapable of caring. In the outstanding issue #298, the Skull narrates his full origin to Cap, demonstrating how throughout his life he's been thoroughly horrible.
So, the best revenge against the Red Skull turns out to be...denying him what he wants. Cap refuses to take the Skull's life, pitying him to the end. In a truly memorable moment, the Skull dies, cursing Cap for his pity.
The Adventures of Captain America was a four-issue mini-series by Fabian Nicieza and Kevin Maguire which retold Captain America's origin with some cinematic flourishes. It was instantly forgotten and remains so, for reasons I'm not clear about. It didn't quite square with earlier versions of Cap's origin, but did a fine job of characterizing Bucky into someone who was a believeable sidekick for Cap. It even wound up influencing a lot of decisions on how Cap's origin was depicted in the movie.
Marvel Holiday Special#1 features a sweet Christmas tale of Captain America by Len Kaminski & Ron Lim. Steve happens to encounter Bucky's sister, who was never told the truth about what her brother did during the War. Cap tells her everything and, to his surprise, discovers he's found a new family.
Captain America Annual#13 by Roy Thomas and Arvell Jones, told a lengthy tale from the Red Skull's perspective, again refusing to make him sympathetic (I think if the Red Skull is ever made relateable it's time to board-up the windows at Marvel and go home). This concerns the Skull's decades-long quest for the long-lost secrets of Adolf Hitler. Amusingly, it turns out to be something akin to Geraldo's quest for Al Capone's vault!
Captain America: Sentinel of Liberty#7 contains a back-up tale by Brian K. Vaughn (then a novice) and Steve Harris. It looks in on Steve Rogers at various points in his life during the Presidency of Franklin D. Roosevelt, transcribing FDR's "fireside chats" from the radio. It does an excellent job of bringing to light who Steve was as a person prior to becoming a super hero, particularly in depicting his mother's death (which had been referenced but not seen). It leads up to Cap meeting FDR for the first time and how FDR's struggle with polio inspired Cap in his mission; it climaxes just before Cap and Bucky's final World War II mission as they hear FDR has died. This is an obscure tale, but find it if you can.
The Young Allies Comics 70th Anniversary Special#1 by Roger Stern and Paolo Rivera takes up in recent continuity where Bucky (back from the dead) has become Captain America. When Bucky goes looking for the graves of his old Young Allies comrades, he's stunned to learn two of them are still alive. This leads to a brilliant scene of Bucky reconnecting with his old friends and finally honouring a 70-old promise the Young Allies made together. Given that the Young Allies were treated as a forgotten piece of Captain America backstory for most of the previous 60 years, this draws an incredible sense of pathos for these people who, in the absence of Cap and Bucky, just went on with their lives.
The four-issue mini-series Captain America: Patriot by Karl Kesel & Mitch Breitweiser picks up Jeff Mace's story, so obviously I was stoked. This follows Mace's life from when he first sees Captain America, to adopting his own identity as the Patriot, to taking Cap's place in '46...only to find the US government isn't too keen at this "outsider" taking over when he hasn't been vetted. The story is mostly concerned with how Mace was just a hair's breadth from greatness, but manages to give him a sense of accomplishment in the conclusion; he loses the Captain America identity, but becomes satisfied with being Jeff Mace.
Captain America and Batroc by Kieron Gillen and Renato Arlem was an odd one-shot which came out recently. Told from the perspective of Cap's foe Batroc the Leaper, it does an excellent job of getting into Batroc's head. Because of Batroc's outrageous French accent (and, heck, that he calls himself "the Leaper") he's been a target of ridicule for decades; obviously, that means we're primed to like him now! There's a great piece about Batroc meeting parkour runners who idolize him and it does a lot to flesh out Batroc as a person; it also brings up Batroc's most memorable quality, his determination to defeat Captain America in a fair fight. Batroc's never been evil, just a crass mercenary and this story understands him perfectly.
There you go; look elsewhere for the Gruenwald recommendations!